I bought my Rupp Roadster 2 roller on Craigslist for $100 and it has both wheels on it and the brake levers and both front and rear brakes work. It is missing the rear fender and I bought a used gas tank on Ebay. Ebay Rupp's tend to be expensive especially for the fully restored ones people ask $1400 to $1500 or more. I seen gas tanks on Ebay for more then I paid for the Rupp Roadster Roller. I will put a souped up Predator 212cc on mine rather than a Tecumseh HS40. The Predator 212cc with just a tiny bit of modification will make huge power and make the bike more satisfying and reliable for a 190 lb adult to ride than just a gutless old 4hp flathead Tecumseh. I may look for a Tecumseh HS40 for a good deal and swap out just to sell it for Top dollar since putting on a clone engine kills resale value on a Rupp.
All you need is a nice thick dense rebonded Foam seat and some people here on the forum make them.
Just got done with a 1969 Rupp Roadster. It's not an accurate restoration, but it's what i could afford to do. When i got it there was no motor and missing a ton of parts. These Rupps make you poor buying stuff for them!
The motor is a lightning coil Tecumseh HS50, instead of the stock H50. I could not find a lightning coil for an H50, so instead I installed an HS50 (and put an old style 1960s logo on the motor.) It actually worked out quite well doing this. It has the 2speed transmission. Also a Dellorto carb. The exhaust I made myself. I could not afford an original exhaust for this bike, man they are expensive! Also the exhaust/intake ports for the HS50 are on different sides of the motor, so the original exhaust probably would not have worked anyway. The custom exhaust cost me next to nothing to make, and it looks OK enough for my needs. Made all the decals myself too. And a weld-on kickstand (originals too expensive.)
Here's my 1970 Rupp Roadster. Not a perfect restore, but it achieves what i need it to do. Another Dellorto carb install. i like those carbs. probably should have stayed with the blue color, but instead went to the more common orange/red color. before and after pictures below.