1998: £90 for 3dfx Voodoo
1999: £80 for 3dfx Voodoo 3 2000
2000: £113 for Geforce 2 MX
2002: £120 for Geforce 4 Ti4200 64MB
2003: £170 for Radeon 9800SE AIW (softmod to 9800pro)
2004: £176 for Geforce 6800
2005: £210 for Geforce 6800GT (new mobo was PCI-E not AGP so needed to ditch the 6800)
2006: £158 for Geforce 7900GTO
2007: £190 for Geforce 8800GTS 320MB
2008: £240 for Geforce GTX 280
2011: £144 for Geforce GTX 470
2012: £208 for Radeon HD7950
2017: £147 for Radeon RX 480 8GB
2018: £270 for Geforce 1070Ti (second hand)
2021: £600 for Geforce RTX 3070
If you top and tail those numbers you can see that over the years I have typically paid around £190 on average. You'll also notice that my current card cost more than double anything I've bought before.
Writing that list it is pretty impressive that the 7950 lasted me over 4 years, although I ramped down gaming quite a bit then due to having a baby.
GTX280 was a bit of a bargain considering it was the flagship card and only released 2 months prior.
The RX480 I bought from a slightly dodgy looking etailer, because it was priced way less than everywhere else and the mining boom was starting to kick off in early 2017 so I wanted to get in and grab a card before prices shot up, given I'd had the 7950 so long. I sold it over 4 years later for more than double what I paid heh.