RCI does
not buy deeds and RCI does
not own any resorts or
any timeshare weeks. RCI is an exchange company --- no more, no less. Period.
Exchange, in the context of RCI operations, is specifically limited to owners "depositing" owned RCI-affiliated resort weeks
on a one time basis for the possibility of obtaining (by "exchange") a different week (not owned by RCI, but owned and "deposited" by another owner)
on a one time basis.
There are RCI
affiliated resorts which are in RCI Points, of course, but that's distinctly different from what you have described above.
Exactly where and how did you come to encounter this "sales person", anyhow? You haven't made that important detail at all clear.
Why would you believe that RCI (or anyone else) can somehow magically "get you out" of your current Marriott deeds --- and for money, to boot?
Perhaps it's a RCI
affiliated resort sales rep looking to peddle RCI Points? (not very likely; they couldn't / wouldn't touch your Marriott ownerships).
Maybe it's a "vacation club" sales operation of some sort? (they routinely come and go). More details on where / how you encountered them would help.
Worst case / most likely scenario is that it's just a scam operation inappropriately invoking RCI's name in an effort to create an appearance of credibility.
The fact that you would be paying out of pocket to "get out of your Marriott deeds" is a big red flag strongly indicating the likelihood of a scam operation.
In any case, proceed with extreme caution (...better still, don't proceed at all).
Something here has a really foul aroma to it.