Hi,
I have also an insulation tester from Bside laying around. It can measure up to 1000V and 10GOhm.
It is identical to the Mastech MS5203 (ans probably some other).
I compared a 100MOhm resistor (with a lot of tolerance) with a real meter and it matches nicely:
The meter itself comes with the test leads and the manual.
I'm asking for negotiable 100€. Shipping is possible.
Best regards
Andreas