The problem with cheap gut is you are taking your chances with with quality control. Yes, some of those gut brands cost 40-50% less, but if you buy 4 packs, one breaks during stringing and another breaks prematurely, what have you saved?
If you are using it in a hybrid as a cross, it might be worth it, but in all honesty, if you are using gut, you really want it in the mains because that is where you get the most benefit.
I'd look at "lesser expensive" versions of name brand gut, such as Pacific Classic & Klip Legend. Pacific recently raised Classic to $30 / pack, but Legend is still $26...for now.