If the T&L engine is indeed new in box, then I would think that whatever Tom's price was would be a place to start. I don't know if I have one of his old price lists or not anymore. (We miss you Tom!) As far as the used ones go, depends on how much they were used , stock or reworked. If these came from the same guy you got the models from, I would not be surprised if he had more than one T&L engine. Probably the same for the ST.46's also.
Type at you later,
Dan McEntee
Same guy, you'll be hearing from me a lot on the Classifieds, and possibly eBay. And yes, there's lots of 51s and 46s, a 60 that I know of disassembled in a box, some 40FPs (some at least that are Tom Dixon modded), etc.
I'm certain the engine is new in box -- it's in the box, in the original packaging with a hand-written note from Tom, and it turns. All of the engines that I've touched that have obviously been in planes are also obviously coated in old castor and will not, or only barely, turn.
I have some of his correspondence with T&L -- I'll look for a price list. That's a good idea, and I thank you for it.