I'm looking to build a budget commuter, based off a rigid MTB frame with fatter road tires, drop bars, and F&R racks. I can easily find a cheap MTB on Craigslist with a suitable rigid frame and fork, would building with decent components on a lower quality frame be a bad idea? I've been riding a late 80's Schwinn World Sport, so it won't take much to seem like an upgrade IMO. Are there any major reasons why I should go with a better frame than the X-brand Wally World bikes? I'd like to keep the entire build under $200 if possible (a stretch, I know) so I want to save money where I can, without compromising the overall performance of the bike.