By far my best tuning equipment investment has been the Tognar base repair iron (really just a soldering gun that keeps the right temp) and the copolymer base repair string (don't bother with the p-tex ribbon, which hasn't given me good results). My repairs with this have been even *better* than shop quality, adhering to just about anything, although be warned that the iron lacks any safety features, so be sure not to burn yourself!
Also, ignore their instruction on how to trim the material and instead do the following:
1. Get one of those cheap hardware store retractable straight-edge razor holders; rectangular, rounded at one end, and the other end the razor comes out.
2. Wait for the material to cool (just a minute or so).
3. Hold the razor as close to flush/parallel with the ski base, i.e., *not* pointing down into the base like you're scraping off wax, but kind of flat like you're flat filing (in days of old).
4. Now trim the excess material: the goal is to cut it off cleanly, without exerting any downward vector, which will tend to pull the material out of the repair.
Hope this makes sense! Hard to describe in writing, but this material has worked very well repairing a gouge that is too painful to relate...