I bought the supplies to make my own, but if you really don't want to do that, I highly recommend www.arthropodantics.com for your ants. His prices are very fair and he is a well known and respected member in the community.
I bought the stuff he uses to make his nests on Amazon because I planned on having a fair amount of colonies, and it's much cheaper in the long run to do it that way. However, I'd you don't plan on making many or if you don't like the idea of making them yourself, then buying them from him is a great way to support a good person who does a lot of work for the community.
If you ARE interested in making your own or are curious on prices to do so, hit me up in a private message. I can hit you with the Amazon links.
Www.TarHeelAnts.com is another great site and the owner there is ALSO awesome. That being said, his prices are a bit steeper and I feel like, until you have some larger colonies, his nests are better for people with deep wallets or who have LARGE colonies that need a more permanent home because they won't really grow much more, so the investment isn't wasted when they outgrow it. (I understand you can move another colony in once it's outgrown, but for me it just isn't worth it.. it may be for others) The mini hearths usually last a colony a couple of months then they move out, which for me and my not so deep pockets, is not very convenient for me. However if you don't care about price, they are great.