Shipping in hundreds of pounds of wild caught clown loaches is far cheaper then tank raising them. Untill we can find a way that is cheap, economical and fast to breed them, 95%+ will be wild caught.
Everything I have read suggests that most of the population is imported from either Borneo or Sumatra, with a few breeders using hormones, but apparently isn't cost effective. Here's some of the articles.
http://www.skepticalaquarist.com/docs/fishes/loaches.shtml
This one revealed an important bit of information. The country of Indonesia (Which encompasses Sumatra and Borneo) has imposed a size limit of 10 CM (a little less than 4") on all exported loaches in order to preserve the breeding population. I was aware of the export restriction but never of the actual size restrictions. That means any loach over 4" in a store is most likely a trade in, or was grown by a distributor to a larger size.
As for breeding loaches. Wild caught ones have better shape and color than many of the bread ones I've seen. That being said the Bread ones are more durable. I would rather gamble on the beautiful wild caught than purchase the less remarkable domestically bread ones I've seen.