You can not pick it up in Tampa.
The only way to truly not get screwed is to have him come to an agreement with your FFL that he ships it to them and then, upon receipt, you (or they) send him the money before they release the gun to you.
Good luck with that, though.
That said, I've never had any issues buying guns online. Do whatever research you possibly can on the seller and deal based on that. Most people who would scam you on certain things aren't stupid enough to scam on a firearm sale.
I've paid the FFL where he is shipping it from and told them not to release the funds until my FFL has cleared the gun and I have checked it. Most are good about doing that.