I remember this too but if you go on what they say that the rough rule is money doubles every 10 years:
£10 in early 80s = £40 now
I also remember John Menzies, I used to get all my games for 99p as this was before any bar codes or price scanning
I used to change the £9.99 price tags with the 99p price tags, until one day I went in to be greated with a huge sign saying 'TO THE PERSON WHO IS CHANGING THE PRICES ON THE GAMES, WE KNOW WHO YOU ARE!'