well, really when buying something privately like you're doing, nothing is safe. If anything the check would be a little better, because you have the ability to cancel a check as long as it hasn't been cashed yet, but still, he would probably have cashed the check by the time you realize he's not sending the fenders. You're taking a chance either way. Even through paypal you wouldn't be protected because it's still a private sale.
You just have to trust the guy, and it's not really a good idea to trust anybody over the internet unless you can get feedback from other people that have bought stuff from that person. If you send them cash, check, money order, paypal, or anything, they will have the money before they send it. So if they decide to not send it, or send you total junk, you just got screwed over and there's nothing you can do about it.