Are you good at bike maintenance? How much time and money would you have to spend to make it rideable?
After a lot of unsuccessful craigslist searching I recently bought a brand new couple model year old Raleigh cruiser for $160. My partner put it together and made tons of tiny adjustments, and it is fabulous for my 1% grade 3 miles to and from town/work. (To my shame, I am only riding about once a week.)
It's a simple enough bike that I don't feel overwhelmed learning the maintenance, but that was definitely something that stopped me from purchasing/riding before. Partner got himself a free hand-me-down bike and we've spent at least $100 on parts, and he has put many hours into maintaining it. It's a good bike, and worth it for him, but seeing that definitely helped me with my decision.
I haven't ridden in years and feel like I know nothing about bikes, but I can tell you that this bike just works. It's smooth and easy to pedal. I wish I could have bought used, but if I had to do more fiddling, or it was hard to ride then I just wouldn't ride and I think the ultimate mustachian bike is the one that you ride regularly.