A dedicated film scanner would be inefficient, certainly. I challenge your assertion that a shop scanner would be better than a desktop scanner/printer from someone like Epson or Canon. I have an Epson combined printer, and a mate has a similar one, cost about £100, and the results are outstanding. The advantage is that you should be able to put a whole load of negs into the carrier in the hood, then, once they've been scanned, apply an action to the whole batch, speeding things up. My comparison of the Epson was with a £35,000 Scitex A3 flatbed scanner, which was actually pretty poor quality, and a Crosfield 6500 drum scanner that I was originally trained to use, and on which I scanned many thousands of trannies and prints for the likes of Titleist golf equipment, (their annual catalogue), and Castrol.
I have a bit of a clue when it comes to image quality.