this may be a regional thing. you're from california right? where bonanza was made and sold... so they are probably easy to find there. And you don't see Rupps in CA because they were made in ohio...
i've had the same experience with bonanza people being arrogant. but again, it may be because here in the midwest, you never see a bonanza. and i've been looking too, yet to find one. But rupps, they are everywhere in the midwest. there's always some for sale here.
some rupp parts are expensive.. but again, stay away from 1965 to 1969 rupps, they are the worst. and hell i don't think they are even that great to ride. but man those bikes and their parts are way expensive. but the 1970 to 1975 rupps on the other hand, readily available and for fair prices. and the parts are way cheaper too. and they ride great! also the 1970-1975 rupp parts are basically all available from black widow. regardless of the price (whether you think it's a lot or cheap), at least the parts are available. and you can see the price going in, before you buy a particular bike. no ebay hunt and peck and bid type stuff.
right now, on facebook market place detroit, there's a rupp hustler for $350. it's pretty complete, sans gas tank and fenders. there's also a complete roadster (predator motor though unfortunately) for $1000... but its been for sale a while, i bet that could be gotten for a lot less. and an Enduro for $700 that's pretty complete with a nice Tecumseh. again for sale for a while, bet it could be bought for $500. of those 3 bikes i like the enduro deal the best...