Personally, I have not had a lot of luck with big-box store bikes; I always end up swapping out components for higher quality parts and find myself spending what it would have cost me to buy a better bike at the LBS in the first place. Used bikes can be great, but make sure you take someone with you who knows a lot about bikes if you are somewhat unsure. Often the LBSs in my area have some used bikes for sale that they've tuned up, and they're usually a step up from dept. store bikes. You're right that you can sometimes find last year's (or older) brand-new bikes for reduced prices. Again, your LBS is the place to check for that. Don't be afraid to ask if they have anything in the back for sale that's not on the showroom floor. Finally, if you're heart is set on the Crosstrail,
here's an example of the next model down from the Sport for $399. Before laying any money down, however, I would visit your local Specialized dealer and ask for a test ride.