No Nitro please, you will "kill" them, they originate from the time when Nitro was only used for
competitions when the price of engine was sacrified for the victory. And use 25% castor and 75%
methanol is maybe the best things to start with.

As for the price - place them on eBay and sale them, the market will set the price. As intial
bargain price I would put 9 USD, i.e. just a bit below the price where eBay is charging more,
in fact check with eBay - in September they had free of charge something offer...

What I would do is to sale them and buy one good new one.