Given most of the electronic goods you buy in terms of AV kit are produced outside of the single market, being a member of the EU means tariffs are slapped on non-EU producers to protect inferior European made products from external competition. Theoretically, if the UK can negotiate a FTA with, say, South Korea - which it cannot do as a member of the EU - then your Samsung TV's will decrease in price as they won't be subject to import tariffs.
Currency fluctuations are a separate issue. Sterling has been slowing down against the dollar and Euro long before the Brexit vote took place, the market just got jittery when it happened and accelerated it. What a weaker pound gives is a boost to exporters and makes tourists money go further.
It will recover, or other nations will devalue their currency to stimulate imports, particularly to the UK as we are one of the most important consumer driven economies on the planet.
South Korea is one of many countries with which the EU already has a Free Trade Agreement. I doubt that the UK will negotiate a better deal than than the existing FTA.
In the 18 months from the start of 2013 until the middle of 2014 sterling rose against the dollar fairly continuously - from about $1.50 to $1.70. For the next 18 months to the start of 2016 sterling fell fairly continuously to around $1.45. For the 6 months prior to Brexit the $/£ exchange rate had been fairly constant at around $1.45. So there is no evidence that Brexit simply accelerated a currency fall that would have occurred anyway.
Markets have simply reduced their demand for sterling denominated assets because there is great uncertainty over what will happen now following the Brexit vote.
Devaluing a currency only gives a country a temporary boost to exports. In the longer term the affect will be to increase inflation as the price of imported goods and services rise. The resulting inflation then erodes a countries competitiveness as it forces export prices to rise again - counteracting the effect of the currency devaluation.
As to other nations devaluing their currencies to stimulate their exports to us which countries are you referring to? Almost all the major currencies such as the Dollar, Yen, Swiss Franc and Euro are free floating. They are not managed by their governments in order to hit specific rates. (The Chinese renminbi is not a free floating currency.)
My main concern about Brexit is still around passporting for services. The trade of goods (e.g. us importing/exporting cars to/from Europe) should be pretty straight forward. Around the world there are many trade agreements on the trade of goods. If it comes to it we can fall back on the WTO agreements on the trade of goods with Europe. However, WTO rules do not cover services as the trade of services such as banking are far more complex.
The key point is that the UK is an importer of goods from Europe and an exporter of services. So falling back on WTO rules would be very damaging to the UK.
Remember too that although the UK is a net importer from Europe trade between the UK and Europe is far more important to the UK than it is to Europe. The EU accounts for almost half of our trade and exports - whereas the UK only accounts for around 10% of the trade and exports of Europe. (This is simply because the EU block is a far, far larger economy than that of the UK.)
The UK's official position now appears to be that we want free movement of goods, capital and freedom of establishment but we don't want the free movement of people. I really don't see why it would be in Europe's interest to allow the UK to get 3 of the 4 freedoms without accepting all 4. It seems reasonable to say that it is all 4 or nothing.
Losing the freedom of establishment would hit the UK hard. Under this freedom you cannot treat countries differently within the EU. In recent years the European Central Bank has been trying to force the "clearing" of Euro denominated assets out of London and into a Eurozone country. (Up to 80,000 jobs in London are dependent upon "clearing".) The EU court has ruled in the UKs favour that such business cannot be forced to be within a Eurozone country because the UK is a member of the EU and is therefore protected by the Freedom of Establishment. However, once the UK leaves the EU then the ECB will be free to force clearing to take place within an EU country and the City will lose those 10s of thousands of jobs. From what I have seen in the City though, that won't be the end of it. Many companies are discussing this and don't like the idea of only moving the part of their business that the have to move to the EU as that would result in splitting their business between London and the EU. If you have to move a large proportion of your business to the EU then it makes more sense to move the whole operation to the EU and have everyone together. Fortunately for City firms they are pretty mobile so moving everything from London to say Paris or Frankfurt isn't that much of an issue. Interestingly, from what I have seen the main thing stopping many firms leaving London now is that there is no consensus on where to go. Not many people want to live in Paris (which surprises me as I like it there) and nobody seems to want to move to Frankfurt. Geneva - the biggest financial centre in Europe after London - isn't in the EU either so isn't a good choice. Dublin is a popular choice though. If one centre does emerge as a viable new base then I think firms will move there very quickly.
I also wouldn't want to be a citizen of Gibraltar once the UK leaves the EU as the Freedom of Establishment has been used against Spain to stop them forcing extra border controls on UK citizens there. Once the UK leaves the EU then again there will be no such rules protecting them and Spain can impose whatever extra controls they want on Gibraltar.
(Then again the loss of the City jobs and the impact on Gibraltar is what the country voted for - nobody can claim they were not warned of these specific effects prior to the vote.)
It is also important to note that the UK is not the only country that has requested to control immigration while maintaining EU trade. In 2014 Switzerland also had a referendum. Theirs was specifically about being able to impose limits on the numbers of immigrants from the EU. Switzerland then tried to agree a deal with the EU to be able to impose such limits (in violation of the freedom of movement) while maintaining access to the EU free markets. The EU flatly refused and talks ended. This appears to have been kicked into the long grass for now as the referendum didn't commit the Swiss government to impose the new immigration rules till some time is 2017 or 2018.
I cannot see any reason for the EU to treat the UK any differently to Switzerland in this.