Oh, these Yanks just crack me up sometimes. As Marion has mentioned a number of times she is in Cape Breton which last time I looked was not part of the U.S.
Similarly, the words "budget" and "Martin" do not run harmoniously together. Guilds are more affordable, but not very much so in Canada where they are not all that common. (Well, I like 'em and was seriously considering one before my fortuitous encounter with Mr Fieldings old Lowden this summer).
The $400 is nice to know, but that's probably why you shouldn't plan on selling it to finance your new one. Someday you will find someone who likes it enough to pay something close to that, but if you are in a hurry you are likely to settle for far less. However, NOW is the best time to sell an instrument, i.e. Christmas shopping season. Try putting an ad in the local scandalizer, ask $300 (plus the cost of the setup; do the setup), mention the appraised value. (You can double your money easily from almost any yard-sale guitar with a straight neck by putting new strings on, tweaking the action, replacing broken tuners, and cleaning it up--you now have a good playable "student guitar" with very little investment.)
The Seagulls, Simon & Patricks, Art & Lutherie models coming out of La Patrie Quebec (guitar town in the Eastern Townships--see lasido.com are pretty unbeatable value if as I infer you're looking in the 'under $500' range.
But since you're hanging around with musicians all the time (or should be), that's one of your best chances. One of them has one too many guitars, due to an impulsive nature...trust me, I know what that's about. And if it was owned by a working musician, it's a players' guitar with dings and scratches, not a cheap imitation or an expensive collectible.