Heh, everybody in this forum is going to tell you (irrationally) to "DO IT!"
Natural reaction from any car enthusiast, of course, nothing wrong with it...regardless, that's what they said when I posted a few months back about a similar situation (I was thinking of jumping to a 330Ci), but when I looked at all the costs involved, I decided I was better off holding onto my (thus far) trusty and reliable 323 until I was out of school and had a ton of extra cash to burn.
Before I give my recommendation, I'd like to know more info about both cars. Since when was ANYBODY offering 24k on a trade for a 3+ year old 323? Most I could probably hope to get for mine might be 17 or 18 (on trade, anyway, maybe 19-20 if I sold it privately), and my car is in fantastic shape with low miles and several months of warranty remaining. Are you trading your car with upgrades or mods that will stay on it? I'd check up on that. Could be one of those deals of a lifetime...or a scam.
Meanwhile, the price on the 330 doesn't seem particularly unusual, especially if you're buying through a wholesaler/small dealership (I know a friend who bought his 323 through a wholesaler, and paid 6k less than what the dealer wanted for what was essentially a great, reliable car).
