I have carried an M&P9c for several months in a tuckable holster from Wild Bills and really like it. I have to admit I usually don't tuck my shirt in but it is designed to do that. When I first got the gun I was looking at a lot of the better known ones like MTAC, Crossbreed, Supertuck, etc. that you see on the forums, but when I saw the Wild Bills at a gun show I bought it and have not been sorry. It's all leather with an offset clip and seems to be top quality and is quite comfortable. It fits the 9c perfectly and the gun rides low and close in the 4 oclock position.
While Wild Bill's Concealment does make some quality gear, I would caution against ordering from their website. In my experience, their customer service is (or was) atrocious (to put it nicely) and their reputation on the various online forums is (or was) pretty poor. Buying their gear in person, such as the gun show purchase you mentioned, may be the safest course of action.
I ordered a belt/holster/mag carrier package from Wild Bill's in early spring 2008. The big thing that pushed me towards ordering from WB's was the great price on the combo sets, and the fact that they claimed that most holsters and gear were purportedly in stock. My credit card was charged upon ordering, but no confirmation or order invoice was ever sent. I attempted to contact them numerous times over the following weeks, to no avail, until I was finally able to get someone on the phone. They advised that the set was reportedly in production, and would be sent out within a week or so. After another month with nothing, I again attempted to contact them. After failing, I threw up my hands and gave up. It was only after I voiced my frustration on SigForum that I was pointed towards other posts on various forums with numerous people with similar complaints. I realized that I should have done some more thorough research ahead of time.
Then in August or September, about six months after I ordered my product, a mysterious package arrived at my door. It was my leather gear from Wild Bills. I will admit that the quality is pretty good, and has gotten plenty of use since then, but the frustrating experience with their online ordering system and complete lack of communication has completely turned me off to them.
One can only hope that they have gotten better in the last year or so. And their website has been revamped, which could be a good sign. They still makes the same claims of "most holsters are in stock" as before, though. Your Mileage My Vary.