As long as you do your research before you buy and you use PayPal. You should be alirght. Like on that first link, i wouldn't buy from him He has a 66.7% Feedback score.
My brother told me (he'* a hardcore ebayer) he doesn't buy from anyone with lower than a 99% score. When i buy i usually try to stick to that.
E-mail the guy if you want and see if he seems legit. The second guy has a score of 230 with 100% thats pretty good, that means 230 people were completely satisfied.
PayPal is a good thing to use, if you don't get your item you paid for they will usually refund your money. Thats why i don't like to use checks, and other forms of payment.
And when biding, wait until the late in the auction to bid. That way you aren't bidding your self up.