Jeff,
I just did search EBay for "neoprene scope covers," as you suggested, and found VERY few that had the forend loop of ScopeGuards, which is just about essential for hunting use--and very few that came in different lengths. Even in stretchy neoprene, one size does NOT fit all.
Also ScopreGuards, as somebody already mentioned, are made in the USA--and aren't exactly expensive.
Somebody in one of the dreaded gun rags recently wrote ScpeCoats up as very handy hunting-rifle accessories.