Ok, so you live in a vintage bike scarce area. There is ebay, and for much less than the Hillborne frame alone, you can dig up late 80's, into the early 90's, when rigid MTB's were still at the top of the line, a pretty good bike for little dough.

Now, there is nothing the matter with the Hillborne. Me, I often lust after its big brother Hilsen.

But that aint happening anytime soon, so to scratch that itch, here is my homebrew Hillborne I'm working on. I'm not much for weekend garage sale scrounging, I got this for about $240 (that includes shipping) delivered to my door, a pretty much stock, lightly used 1988 Bianchi Grizzly. I've swapped handlebars and saddle, got a few other things to do, but that is all personal stuff, it was fully ready to go out of the box. W/some smoother tires and some fenders, which I may do, it almost could get a little faux 650b look going:



So, nothing the matter with the Riv option, but there are other paths out there esp. if money is tight and w/google, etc, you can gain information pretty quickly. FWIW, although it is becoming less common, you can find stuff like this for *lots* less than I paid if you are willing to do some legwork.