With a $100 budget, you can do a lot better than a model 8.
Look for a concoa 212 or 312 series or an airproducts/airgas that starts with E12 and ends with a B or a C. Also try searching for a victor vts-250b/c. There was even a new victor hpt-500 available in your price range the last time I checked. If you are patient, you'll even see stainless parkers in your price range.
Agreed. There are a huge number of dual stage regs, some new, that you can buy with $100. I don't know why you're looking for only a Matheson ...many models are quite nice, but they're only a fraction of what's available to you at a similar price and quality.
Concoa 212's and Victor VTS250's are my regs of choice. I also recently fell in love with GO regs, and I've taken a liking to Betta's Parker IR6000's.