You are pretty safe in assuming that Le Jardinier refers to the name of piece and not the artist/sculptor. I know that Jean Garnier did some pieces like this, and he did do one of a gardener, but it certainly isn't this one.
I would be extremely cautious, make sure that it is bronze and not spelter ... certainly ask for more photos, some nice close-ups so that you can see the quality of the piece, including the base and underside. Also a shot without the shade on might be useful.
When they say it's 2' tall, does that include the shade? If not, it is going to be quite a tall lamp. Most pieces this size would, I thought, have been signed on the base somewhere.
Not sure what the others think about this one...?
