Its hard to get a proper baseline on pricing when prices jump around so much.
Here is quick compilation using pricespy, showing the 980ti, 1080ti and 2080ti. I've tried to line up the timelines by eye.
The 980ti was usually between £500 and £600 but there was a period in the middle where prices dropped as low as £3-400, in the second half of 2016. Then jumped back up to £500 at the start of 2017.
When the 1080ti was released it was initially around £700, then when the mining boom occurred in early 2018 they rose up to £800 and never dropped from there.
The 2080ti started at £1150 ish and has fluctuated between around £1100 and £1150 ever since.
What's most interesting to me here is not the 2080ti but the 1080ti. Oddly it was best value at launch and later offers/discounts were poor.
It looks like all the damage was done in that one year, from July 2017 through to Summer 2018.
The only card to display what might be expected is the 980ti. It started high, dropped a little after launch, then stayed level for a while, then started to fall in price just before the 10xx range came out.
