The 24 hr time limit without cancellation is OK. If it can be can be cancelled you will get trolled with useless 1 token offers and won't be able to tie down their tokens for 1 day. I'll suggest you make friends with active higher level managers in your server. I have about 5 of such managers that buy 59% players from auctions at the beginning of each season but I see these players as 99% bcus I'm - 2 level. I'm already done with negotiations this season I bought 2 young players with special ability from this managers, they accepted in less than 2hrs if I could communicate with them I'll tell them same time next season!