I do own one (sob, only one) MecGar 17rd. Until I found it hanging on a peg hook in a gun shop (standard MecGar packaging) about a year ago, I had never heard of them either. Works great and fits flush. On the left side, it has the MecGar name and logo, and the designation: "MG-P226-17" Witness holes on the right side are marked 5, 10, and 17.
The gun shop owner knew what he had, but sold it for the marked price of $40 because he thought it was a fair price. He also sold me a new factory 12-rd P229 .40 mag for $40, the only one he had. He told me about another store in town that might have P229 hi-caps, but that their prices would probably be more like $80-90.
Have never seen or heard of a MecGar 17 before or since.