You know, I actually looked into this at one point - not exactly for the same reason, though it did play in. Some deeded resale weeks (only through Marriott's TS department, I believe) actually allow you to receive MR points instead. Technically, it worked out to cheaper than purchasing MR points, and did come with some cool perks/options. Unfortunately, I don't actually value MR points at $.0125/pt, and couldn't bring myself to seriously consider it.

FWIW, some Marriott TS properties (high demand weeks, not really sure about points) hold their value surprisingly well, even on the resale market. Never a guarantee that it'll continue that way, of course.