I've got a plain round drum on my bow.
Holds about 15 yards of string(fortunately that's just a bit longer than my basement).

I'd love to get an AMS retriever. My friend has one, simple, easy, and fast, but pricey at $80 around here.

I grew up bowfishing with my Dad's old Bear brushbow that had a 20 year old homemade drum on it.
It was basically a 1" x 4" board mounted to a 1" x 1/2" board that was taped to the front of the bow.
It had an aluminum tab nailed to the side of it to grab the end of the string. Worked great, lasted a LONG time, and cost about 25 cents.