I'd recommend DIY. simple nylon tube with drawstring at either end. Could cut up a pair of pants (ECWCS rain pants if you want goretex) and have half the work done for you already.
I've made a few pull-on gaiters because I too hate velcro. I pulled a pattern off my OR gaiters and just eliminated the overlap on the front, I like the shape because it covers more of the laces on the boots but no reason to go that fancy if you don't want.