Noticed you will be fishing brooks/rivers. I fish brooks and rivers and have gone to buying cheap (100.00 or so) breathable, neoprene foot, waders.
If you are fishing properly, no matter what you buy will be pretty much shot after a season's fishing. I once had "Kevlar" reinforced waders and they lasted about one season.
You did not mention if your budget had to include boots. Wading boots will be around 150.00 - 200.00 for anything worth buying. If 100ish has to include total wading set up, you will have to buy bootfoot waders.
(No ankle support)
IMHO go cheap on the waders and spend your hard earned cash on the best boots you can afford. One twist of the ankle can change everything!