Well, the easy way is to buy a bike, post it on road forums or single speed forums, and if/when they run down your bike, you probably can come here and join the party....

Used is not new. I bought a 2003 bike ridden six miles and wrecked, with no damage to the bike but a lot to the rider. I consider it used. I'm sure the seller considered it new, eh?

Classic denotes style, type, exactly as Little Darwin states. I have a Ti frame that is certainly not vintage, it was not used, but its lines and accoutrements are classic. Classic styles can be enduring if they continue to meet evolving needs and standards, but they can also be classic and non-enduring, such as the fins on cars of the late 50's and early 60's.

Vintage is age, categorical, and certainly would not be current, regardless of classic styling. It represents a time period past, not a style. A 1964 Schwinn Heavy Duti is vintage and classic. The 1964 West Point banana bike is vintage, but certainly not classic. And you can still buy a classic Cinelli lugged steel frame, but it's not vintage. (When you get the bill, however, the sticker shock is classic.)