I've found that 'completing a rainbow' is extremely difficult. Despite buying virtually everything as and when it came up (including winning almost every bid for item on ebay), for some players it just doesn't happen.
I STILL haven't seen an orange ( /11) base card for Joel Ward despite still watching all ebay variants every day for 3 months now! I'll admit that is a bit unusual, however the 'Premier Gold' (1/1) finish cards are also as rare as hens teeth, and I'm finding that ebay is really drying up now.
I guess that this is 'true' collecting - with my old cigarette cards, there are a few I have been waiting for, for over 20 years now. Admittedly I don't actively search for them daily, but I do have ebay 'watches' set up to alert me. I did think I'd have this over with fairly quickly, however it looks like it will be one that is never quite complete. The few cards I want could be in unopened packets for years to come!
In answer to the question though, typically for Palace players, the typical prices have been
premier gold £65
Topps authentics blank backs $10
(that's if on ebay.com auctions)
The other main issue for me of course has been all the postage, but I try not to think about that!!