A quick search on Craigslist for Grandma's Marathon will show you plenty of things for sale.  It's like a black market for Grandmas Marathon entries.  There's also a lot of lodging options for people desperate for even a place to pitch a tent. 

It should be known that Grandma's does not condone the sale of race entries. There is a transfer fee, but those must be made before April 1st, so at this point it is against the rules to buy someone's entry and use it as your own.  It could jeopardize your eligibility in future Grandma's races.

Also be wary of scams that could come out of buying lodging from someone.  It's not difficult to see how someone could steal your money, and you end up without a room.

That being said, there is a lot of trade that happens on the sight.  Here's just a few examples of what you can see on Craigslist:

 

Craigslist.org
Craiglist.org