Look around for used ones. Starrett, Brown and Sharpe, and Mitutoyo are all good brands. I used to sell Central and Fowler. Both are cheaper to buy and not bad for the price. I would stay away from the Harbor Freight brands.
Is it a bad idea to get a Starrett or mitutoyo brand dial and swap it on a cheaper tool like the Fowler or should I just keep a look out for a good used piece?