Ok how many bidders do you actually have participating on this site? You have to buy credits to bid (which is wacky), but I cant find any info on how much credits cost. This seems pretty strange.
No you don't have to buy anything, purchasing credits is optional and 1 credit=$0.01. It's a bartering site so you post items for free, earn credits from bids placed on that item, and use the credits to bid on other items.
You only buy credits if you aren't going to post anything, but you never need to buy anything to use the site.