I think they are Line 20 snaps. You can get a bag of them fairly cheap from Tandy, but make sure you buy the accompanying snap setter. It is usually a little more expensive - around $10, but you only need to buy it once.
Regular old barge cement I buy at Walmart. It works much better than the regular leather glue you can buy through Tandy or Weaver. It's probably a bit of overkill for something I was only going to wear once for Halloween, but it works great for all projects and it's super cheap.
