I doubt it. The Ray is worth way more than 300 dollars.it could be legitimate. The guy was just covering up his location on here because he know his thread would be closed if he posted his real location. The buyer would be covered by ebay/paypal if he doesn't deliver the goods. I'm sure there are some members on here that got rays in states where it is forbidden.
Here's the same ray listed for $700 dollars-http://www.monsterfishkeepers.com/forums/threads/for-sale-stingray-9-hybrid-male-700-sulphur-la-shipping-only.652741/#post-7365693
And on January 20th he ( M monsterfish08 ) tried listing it again for $300 dollars but a mod deleted the listing because it was listed in the wrong format.
However, if you're sure it's legitimate and low risk to you go for it. It's a heck of a nice day at a even nicer price.