welcome to the forum, for that kind of money i would think you could get a decent unit, but like you i'm not sure you need GPS, 3k acres is small enough you could trinagulate all your spots, but the newer GPS units sure make it nice, i don't have any (not much anyway) experience with hummingbird, i used to use there flashers eons ago[:-], i mainly use lowrance and eagle line of electronics..
but i have heard good stuff about the new hummingbird line-up
you might post this question at bassfishinghomepage or bassboatcentral, some of those guys my be able to give you the lowdown on the unit your looking at