I have a bunch of used ones (currently stored in a diaper genie) you can have for the cost of shipping...
Walmart seems to have fair prices. Just buy them some from a place that they can return them. We had to try a few brands to see what fit best, and settled on Pampers. Not all kids are shaped the same, and pampers worked. Their expensive model has been rated the best for containment and met that challenge for our daughter, the extra buck or two a pack of insurance is worth it to me, explosive diapers = bad news.
Anyway, you can buy the cheap brand, just get them somewhere the parents can exchange them if they want to, walmart, target and most grocery stores will let you exchange unopened ones.