Most synthetic gut reels are way under 100, with Gosen being the heavily favorite on this board....
For multis it'd be Pro Supex Maxim Touch, Mantis synthetics also get great reviews so far, and are really popular in the UK...
Way too many poly reels under 100: Topspin, Pro Supex, Genesis, PolyStar...
If youd like to look at natural guts too, even though they're not available in reels, I think Global Gut at $10 a set is a highly justified price.