I agree, I’d pick a known brand, read some 5 year old speaker reviews and search the classifieds. Second hand in good condition probably 40% of new price then. So look for £1k set ups. Speakers are the most important part so don’t waste £500 trying to purchase 9 speakers. I’d start 5.1 or even 2.0 with that budgetFor £500 you would be better of doing it bit by bit. Front three or just a stereo pair first then add as the budget allows.