If you hang around the C&V forum for a bit you will realize that the bike industry has been churning out vast quantities of adequate-quality adult-size bikes for 45 years. (At the same time there's been a lot of disposable department store junk.) I don't mean bikes for racing, I mean "just a bike" for riding around. There was a turning point in the 80's where people walking into a bike store looking for "just a bike" walked out with, not a road bike, but a MTB. There was another turning point in the 90's when MTB's got good suspension and therefore more expensive, and people buying "just a bike" started buying hybrids. Recently there's been a turn back to drop bar bikes. But in any case they're adequate for commuting, and on Craigslist they cost nearly nothing - like two or three tanks of gas. Every part on it can still be replaced with something compatible if it breaks.

We on this forum get nerdy about this stuff, trying to pick out the best value for money or placing limits on what's good enough to be acceptable. For myself, I have a heart bug so I really prize low rolling resistance, and a little nod to weight and aero. I'll never buy another stiff, heavy tire. I look out for parts that aren't fragile or susceptible to rust. I'm not hung up on brand name or business model of the seller. I've built my current bike up from a frame with both new and used parts, but I see that if I took my preferences and applied them to a new bike, I'd wind up in the $750 sort of range - still a great value compared to $20k for a Civic.