Leakdown test. Interesting.
Seems like it's possible to do that yourself, but maybe the gauges themselves are expensive... I'll look into it!
Way late reply, sorry!
Yes, it's entirely possible to do on your own, the tools are affordable. The big concern is that if you give the cylinder too many PSI than it can take, you might drop a ring.
Leakdown gauge sets are not cheap, you're right there, but it's not a simple process either. There are some tricks to getting accurate readings during a leakdown test. And then there's interpreting the data that can be confusing.
Leave that one up to an expert.
A couple guys have mentioned it here already, but the reasoning was incomplete. Yes, the valves tend to beat into the head, but the reason they burn is because the valves hang open, not because they are beating into the head. A simple valve adjustment at the right time can save you thousands. These Tacoma motors burn valves and crack heads at the same time, and a leakdown can catch that before it's a problem.
Edit: looks like Matt's got you covered with a better response.
In the long run, a leakdown from my usual shop runs me $150, which is still less than a decent gauge set for doing it at home. Plus, having a pro who knows what he's up to do the test and handle any liability will always be a safer bet. A good shop will give you your PSI ratings by cylinder on your invoice afterwards and not spin it into a sales pitch.
When purchasing, I would never buy without leakdown numbers and a written inspection report from my mechanic. It's the best way to know what's going on inside your engine. If a cylinder reads abnormally low they can bore scope it and tell you if it's a valve, valve guide seal, piston ring, cylinder crosshatch, or head gasket issue. It's worth every penny.