It is not necessary to have purchased the Strongholds document in order to use this. This product can stand on its own as a way to quickly stock a marketplace.
The epic merchants in particular are very amusing and will likely be over represented in my games. In particular I like the Fey Bargain and Needful Things merchants. Having a way to generate supernatural bargains on the fly is immensely helpful!
[5 of 5 Stars!]