I bought a 1984 or so Centurion Elite RS years about 5 years ago for $100 . It was like new , no scratches or abuse and it was my size . The original owner never rode the bike, it just sat in his garage.I did not buy it to flip but after riding it for about 2 years , I decided it was a bit too modern for my taste. It rode very nicely and had some very nice components , cyclone derailleurs , gran compe brakes and very nice bronze anodized wheels. This was an upper tier bike with sport geometry that was fun to ride. I listed it on Craigslist for $300 and it sold to the first guy that looked at it! All I had in it was a set of tires I already had in my attic. I took the profit to fund my purchase of a 1977 Raleigh Competition GS that was in the same pristine condition as the Centurion. I paid $300 for that and still ride it regularly. I can’t imagine actually making money flipping bikes , maybe when I retire in a couple of years.