If you really want to get rid of them, list low prices, at least 50% of retail. If you are more interested in recouping money invested, search eBay for similar completed and current items. If there appears to be a market for a particular kit, list it there. Of course, the eBay way would be more work and not every kit would be worth eBaying.
My experience is that if you list your kits and ask for offers, you will not get as many offers as you would for a kit list with prices.