Aside from a bid system, a continual rolling list works better than just by record. Once you make a pickup you go to the bottom of the list which rolls over for the next week. Probably the second most common type, but wanted to put it out there as an option vs bids. It might be an easier sell (depending on the league) and is certainly less involved than managing ww funds.
EDIT: Also, adding a fee is great, but you still want people making moves as that is half the fun. Have a $1 fee in one league, which makes you think a bit, and a $5 fee in another that is probably a bit too restrictive for my tastes.