Still not quiet following your logic on the 3080ti. If the cost of a PSU upgrade made you reconsider and return it.... now your thinking going up to 3090s?Perhaps it is worth to upgrade the PSU and get the 3090 instead. I've seen it go for €2k.
The 3080s are the best bang for buck if you can find one. Best chance at getting one for RRP is the FE cards. You mention € so guessing not UK based. Join an FE Part alert Telegram/Discord/Twitter and be ready and setup with an account on the retailer for your region.