u think this is legit and will work???

Probably (to both), but there's always a risk in buying through eBay (do not ever pay through "Western Union", because it is often used by scam-artists, but use PayPal or a credit card directly).

If you buy from an actual store (physical or web store), you will have better guarantees for refunds and returns (if it doesn't work, for example). With an eBay purchase returns/refunds are difficult at best, and most times impossible.

if u still wanna get it cheap but dont wanna trust that ebay seller go to www.memoryx.net they have it there for 79.98 dollars
http://www.memoryx.net/xrv512.html