Personally, I wouldn't have spent the cash until the guy told me he had it and it was working. You know, just in case...
But if you are so certain it was working I'd still press forward with the insurance. However, if dumpster diving is all you feel you can do, good luck. It really isn't "illegal" it take items in a dumpster, but it is illegal to pilfer through private property, and most companies consider their dumpster just that. I've heard of mild success stories of people getting a few PDAs, and stuff out the back of CompUSA,Staples etc, but if you live in a town that is even mildly large you can forget it. You'll either be in competition with umpteen other people or else the law will be patrolling the lot due to excessive "visitations".
While it was said harshly earlier, your best bet would be to ask your parent(s) for the cash. Explain the situation and tell them you'll pay them back(somehow).