Really depends. There's always risk involved in these lockers. If you only bid on what is actually visible, you're going to have people outbid you on them, because they see the same things usually. There is a touch of blind bidding that has to be done, based on what you can see. Obviously you don't see $500.00 worth of stuff and bid $2,000. But you are going to take risks in this.
It's the nature of the beast. One thing you're doing right: You're not buying just for the sake of it. If your seed money is all you can spare, and you can't waste it, then don't piss it away just to buy a unit.
Watch the auctions, see what is going on, but remember that these things are like playing baseball. A base hit is what you're after, not the 'home run'.
Take your time on it. Some of the more experienced storage warriors will be in with their advice. I'm new myself. But, while I'll take some risk with units, I am not interested in throwing all my money down a hole and hope I find Al Capone's lost money.