There's an assortment of vendors that sell a pre-assembled kit of tools needed to build different RV variants. From the VAF forums, it seems like most of them have had favorable ratings. I decided to go with the kit from Isham (e.g. planetools.com), which has a specific package for the RV-14. It certainly wasn't cheap, but previous builders seem to be happy with this particular kit.
The high-dollar items in the kit includes the seemingly ubiquitous DRDT2, a rivet squeezer, rivet gun, and a pneumatic drill. I wasn't familiar with using many of these tools up front, so I didn't have much opinion on the upgrade options. In retrospect, I think I may have invested in a nicer air drill, as the one in the base kit can't be throttled at all.
The rest is (hopefully) most of the bits, clekos, rivet sets, dies, and hand tools needed for the project.