Well, at a price limitation of $100 for a true 'In-Line Rotary Vise' (ILRV), you will probably not get any recommendations other than a Danvise.

The question is, do you want or need a true ILRV? If yes, than you've just about made your choice. If no, than you can continue to use the Thompson (I've had mine for over 35 years and prefer it over several other vises I have). You might consider getting a set of different jaws for the Thompson including the Magnum and Midge depending on the variety of flies you tie though.

Deezel