I buy a card for $25 bucks that gives me 7 small buckets, so that figures out to $3.50-something per bucket, or about 9 cents per ball at approx. 40 balls in a bucket. If you just buy 1 bucket at a time, I think it's about $5 bucks a bucket.
I'm not sure how much a large bucket costs, b/c I usually hit only smalls. I use them at the chipping area first, pick them up, then go hit them on the range. A pretty good deal at our course, IMO, and the range balls are usually newer, in good shape.