One option is to rebuild the Belleville stack. I've set up regulators in the range of 1000 - 2000psi many times but it may seem daunting if you only need one. The nice thing is that once you know how, you can set it up for pretty much any pressure you want.
If you want one that has been configured for a certain setpoint, the only place I am familiar with is the shop in CA that is banned on this forum.
Another option is to put a WTB ad on the classifieds and perhaps someone can perform the service for you.
Regarding what you've heard about other regulators, I agree. I have tried several other brands and an large percentage have had a tendency to creep so I stick with Ninja.