The problem I see is setting a flat number per day is the members could be giving away more packs of seeds per day than they can hope to get in return. For example: 19 members each select five packs of seed from me the first day. That's 95 packs of seeds requested from me, but I can only pick 5. If the swap runs for two weeks,the most I would be able to pick is 70 packs total, less than I would have give away on the first day.
Here is a thought if it's not to difficult to program. Start everyone with 5 packs per day. If a member receives more than 5 request from there list, then their available dibs would increase by that amount up to a set maximum, maybe 10 or 15.
So if I have 5 packs or less requested from my list then I get 5 dibs. If I receive 8 request for my seeds then my dibs would increase to 8. It would increase every time someone picked from my list until the daily maximum was reached.
