it sounds like you don't know jack about cars in general...

first off a complete swap will run you a few thousand anyway... so whats the point of going high miles and swapping? secondly, once you swap your resale value shoots to a fraction of what it originally was.

so now you have your inital cost+the swap+the resale loss that you are dealing with. i would consider this choice to be the less frugal one, and if your budget is 6k i'd think you'd be looking for a 4th generation because unanticipated and scheduled matinence on a 5+ year old car will be north of 1k a year.