Good question. First issue is that you really have to custom build a body to fit them between the extra cavity space for the board and the front rout for the dummy. Second issue is that they need some careful tuning, and older sets may need updating to perform well. Third issue is the need for a blue box, which would make it a complete package.
It would probably cost you at least a couple grand to buy a new set from Alembic, maybe more. That said, it's worth what you're willing to let it go for. It's also worth what someone else is willing to pay for it. If those numbers overlap, you can make a sale. If they don't, one or both sides will have to re-evaluate their value position or you get to keep them.
As far as a suggestion goes, I'd offer them for what you paid if you can remember. Make sure to provide pics detailing everything you have so there is no confusion. Also, can you confirm that everything works, and will you stand behind them if they don't?