Selling collection

Depending on how much effort you want to put in, IPMS or ebay as others have said.  The lowest effort, but probably the least profitable is to contact one of the dealers that has an ad out in the back of FSM.  They will drive out and give you a price for the entire collection, then pick it all up for you.  I've recommended that to a casual aquantence whose husband had passed away with a big collection.  She was happy to do it so easily.

GreySnake

When my father died and left a lot of kits I wasn't interested in. I contacted the local IMPS chapter to see if they were interested in the unbuilt kits. A gentleman came out and bought the entire collection for a fair market value. So if you have a local IMPS chapter you might want to drop them a line at least for the kits still in the box. It removes a lot of the hassle with selling on ebay and the fees.

Great advice!

When my father died and left a lot of kits I wasn't interested in. I contacted the local IMPS chapter to see if they were interested in the unbuilt kits. A gentleman came out and bought the entire collection for a fair market value. So if you have a local IMPS chapter you might want to drop them a line at least for the kits still in the box. It removes a lot of the hassle with selling on ebay and the fees.

I’ve been thinning my stash out on EBay.  Takes some time but it’s quite easy.

OK, I'll bite. PM me a list.

Ebay

Craigslist 

Letgo

Offer up

Amorama.com has a buying and selling section

Get a vendor table at a local hobby show

Get a table at a flea market

An ad in FSM Magazine