I went to my local H-E-B this evening and found this for $2.50.
Lot's of trash in here, but looked like a few possible winners.
T-Hawk (a converted Foundry Street Violence mini) here volunteered to model for size comparisons. It looks like the cows will work, but the pigs and sheep may be a bit to large. On the other hand, I've seen some big pigs so some of the might be tabletop acceptable. I'll be using the larger BS minis, so that'll help bring the scales in line.
The horses and dog were way to big to be usable. That's ok, I've got the horses covered, and I'll be getting a stray in the BS tombstone set.
Regardless, at least 4 workable cows for $2.50. Not to bad, I guess.