There are a couple of issues here. First of all, it's relatively common for large forums like FX-Sabers to have buying and selling that involves gift payments to avoid Paypal fees. Frankly, I don't think it's fair or responsible no matter the context and no matter the reputation of the seller, but I have done it a few times because it's simply how certain people operate. That being said, when a seller operates through eBay, they should not ever deviate from that, and you should never agree to purchase something outside of eBay. It would be easy enough for him to create a listing specifically for you to sell you the item.
The other issue involves the history regarding tattoosby5. It sucks that so many people on this forum lost money to MachinedFX, but that happened before my time, so I can't comment on it. I've recently become interested in the Starkiller saber sold by tattoosby5, so I went about contacting about 15-20 recent customers. The overwhelming response among these customers was being impressed and happy with their purchases (this includes Starkiller himself, Sam Witwer). If you're really interested in what he's selling, simply buy it through eBay, which gives you all kinds of protections against fraud.