I have no experience whatsoever with this seller, but I'd stay away it I were you.
Here are my reasons: although I am not an expert on Lady Gaga, this signature looks shady to me. AND it is not exctly a very beautiful example either - in my opinion!!!
Everything that makes this company look pro to you is based on their claims:
-been in business for 7 years (but on ebay for just 6 months!!!)
-already has several negative feedback on ebay and a total of just 164 ratings so far
-provides photos as proof (yeah, photos of some person whose face can't be seen with the celeb, could be anyone!!!)
-they have a nice lil story on where they obtained the signatures, anyone can come up with that. Some stories are actually quite hard to believe in my opinion
-IF they are legit, they are - judging by the pics - obviously obtaining them by jumping at the celebs before they have a chance to get outta the car. I personally am not supporting this behaviour, but some will have a different opinion on that. Fine with me, I just needed to say that!

-A lot of the autographs are too cheap.
I might be wrong, but I certainly wouldn't buy from them. I agree that they are trying to look very pro (especially in the Gaga auction), but the attempt itself isn't very pro in my eyes.
If such an autograph is your greatest wish, make 1000% sure that you are getting the real thing! The proof offered here proves nothing!