It depends upon how much money you need to get from the collection and the amount of effort you are willing to expend.
1. Least money and least effort. Sell the entire collection to a local hobby store. They will look it over, cut you a check, and haul it away. It can be done in just a couple of days; but, you will get pennies on the dollar.
2. Medium Work and Effort. Sell individual kits at model shows or local club meetings. This requires renting tables at a show or shows. Assume that each show will take a full weekend and that it may take several shows. There will be a percentage of the kits that no one will buy. You will probably get dimes on the dollar.
3. Most money but lots of effort. Sell the kits individually on eBay. This is a TON of work to photograph and list each kit, and then box and ship each as it sells. Some will likely sell for much more than the purchase price, others for much less. This is a ton of work.
Another option is to donate them to a local model club - you won't make a dime; but, they will be gone quickly and the club will benefit. I've told my wife to donate mine to the local IPMS club for their annual raffle.
11. February at 04:46:02