If you can spend the extra the TSS goes for $700-1100 used. PL3/Ultralyte 2020 would be good for basic testing and for any major install issues. For the newer Stalkers they go for $2000+ which is a tough pill to swallow.
Conventional wisdom around here is that you should test against the hardest gun you are likely to face. You can also ask for help from a tester on here with the guns you need in your area. Everyone here is pretty damn helpful, from my experience.
If you don't want to go down the rabbit hole of getting into an expensive VPR gun, a Truspeed 20/20 seems to be a well liked choice around here. It is a very narrow beam pattern, so it is much easier to find weaknesses in your install.
Want to go even lower in price? I love my UltraLyte LR B. It is also good at finding weaknesses in installs (not as narrow as a Truspeed 20/20, however) and it is a very fun gun to shoot.