How to choose a penny-auction site

There are dozens, if not hundreds, of penny auction sites out there. Usually, you have to buy bids in big packs of 20 or 30 and of course, those bids only work on that site, so you can't just flit from site to site. Here's some hints:

• the products -- watch for a while and make sure they are selling things you want. That's things, plural. Don't buy a $50 bid pack, win or lose one auction, and then realize you have no further use for those bids. And very few sites offer refunds on unused bids.
• the prices -- on sites with lots of users and few auctions, you won't get much of a deal.
• the reputation -- on a site with few users and lots of auctions, you ought to get a better deal, but ask yourself, if the deal is so great, where is everybody? Before putting down your hard-earned cash, scout around the Internet a bit and see what other people think of the site.
• the extras -- check out shipping-and-handling charges (which can take a big chunk out of the savings), the help section, the return policy. Be smart.

You know what I ignore? The price of the bid. It just isn't very important. A higher bid price means a lower winning price and vice-versa, so I figure, anything in the 50-cent to $2 range probably evens out.

I encourage anybody with a story, good or bad, about a specific site, to put it in the comments.