Rototimes could be of some help.Link
I have yet to find a site with GOOD auction values. Rototimes is ok, but I rarely agree with them. I think it is actually quite hard to come up with auction dollar value figures prior to a draft. One round in and all the values have changed. If too much money is spent early then cost will go down later, but there is better value later. If little money is spent early then others have inflated values.
In my keeper auction league you have to take into account keeper prices and what players are going to be available at different positions. Then who has what money to spend and what they need.
If it is a redraft league or a league starting from scratch, then take a site like rototimes and make your own adjustements. Auctions are much harder to prepare for than snake drafts.
I usually take 4-6 sources then compile their rankings, and then adjust according to my league's setup/scoring system, and adjust according to my rankings, and then take the keepers out of the rankings and adjust again.
Lots of work for auctions, and I spend much more time on them. I guess that's why I usually draft horribly in snakes and quite well in auctions.