It may seem high if you are new to pay telly but virtually every year the monthly sub has increased so a pound or two increase is far more palatable to people who signed up when it was cheaper and offered far less.
SKY like VM have not looked to reduce or freeze the price of the main product but have increased the value by offering cheap or even free secondary services, for SKY that means cheap broadband (if you are in their LLU area) and cheaper phone calls. If you can not or don't want those bundles then it's almost like paying more than other people for less.
As a new customer you will get prices and deals that are not offered to existing customers but that rarely means lower cost subscriptions, that's where SKY make their money and recoup the subsidy on the low cost hardware and install.
At the end of the day add up what you spend on non-essential entertainment in a month, things like the cinema, take out, drinking and smoking etc etc as the amount would probably surprise many, the cost of SKY is then relative to how many hours of entertainment you and yours get out of it.
Another option is Freesat HD, granted the equivalent set top box to SKY+/SKY+HD costs around £290 plus install but you do get BBC HD and ITVHD so some HD footy plus most of the "free" channels you get via a SKY box. You can also look at Setanta on Freeview or on a SKY Dsat non-subscription setup, you pay them directly
The MIX package is a huge profit maker for SKY which is why you have to have at least one, the cost pads the profit but also subsidies the premium packages mostly sports it has to be said. When SKY's Premier League contract is over £1 Billion for three years and then add on all the contracts for other sports it puts the cost of SKY Sports into perspective. Setanta who charge roughly a third of the price of SKY Sports have a PL contract which costs them about a third of the price to buy and offers a lower rated selection of games (as defined by the PL when they created the packages) that reflects their pricing to the consumer.
Pay telly is not for everyone but like most products and services if you use it enough it becomes very cheap and very good value, you just need to decide if you would watch enough footy matches and other content in HD to justify the cost. It's no different to spending the money to buy a large HD telly, a PS3, 360 and a HD DVD player plus buy/rent movies, you judge if it's worth the price