I would never take my car there. Their reputation is that they always try to up-sell you on things you don't need. I've heard from friends that they asked for transfer case fluid checks but they were never done.
As for transmission flush, that is the last place I would go. Many of the generic shops that do tranny flushes uses Dexron as the flushing fluid. Then they add a bottle of friction modifier at the end to make it behave like OEM fluid. But most car makers now recommend a synthetic or semi synthetic fluid and that stuff is expensive--upwards of $5/quart. You need at least 13-15 quarts to flush a tranny. So all those $79 flushing prices are based on Dexron.
Read this article on transmission flushes
Transmission flush, transmission service.