I've read you can make big money enchanting stuff with these. The wiki says it is random and hard to find the items to disenchant them. I thought I'd ask you guys the best place to maybe look.

From what I've heard, a waterbreathing enchantment is harder to find after level 1. The best luck I've had with it is Nazeem carrying a necklace with the enchant, I think. You can also look at the Radiant Raiment in Solitude as they carry enchanted apparel. Muffle is just a pain in the ass to find. Just keep looking at blacksmiths and you might find it.