When I do auctions I don't usually have a set end time. I just say 24 hours from the last bid is when it ends. That way if someone has plans or something they have an entire day to get online and bid! That might help?
Man I will try, but they'd probably be a lot more basic than these. It's hard to justify making really nice adopts when the customary flatrate for them on dA is around $8. So if I make any that take about 45 minutes each, I will do that.
Alternatively, if you catch me during a stream, I could do a custom flatrate one! I post on tumblr when I do streams for these guys. I'll try to remember to post a journal here too when I do!!