Source-measure test system: build or buy?

During my last summer of college, I worked for a power-supply company characterizing transistors with a curve tracer. Curve tracers are no longer manufactured, and engineers now either use a source-measure unit (SMU) or they build their own with a computer, a power supply, and a DMM. What have you done when you needed a system to characterize devices for DC characteristics? Have you purchased an SMU or built your own system? If you bought, what tipped the scales that way? If you built your own system, did you save money? How long did you spend programming the system? Whichever decision you made, was it the right one? Or, perhaps you found a curve tracer, either in some back room or on eBay, that you use instead.

Feel free to comment or send e-mail to m.rowe@tmworld.com.