In pricing the programs, fixtures, etc...
How would a machine tool dealer value these things, if they were selling "new" machines, tooling, toolholders, fixtures, etc...? They'd cost out new items, estimate how long it would take to do the programming, work instructions, engineering, etc, mark all of it up, and submit a quote.
Now, most of that is behind you, but I bet you have some idea what it would cost in time, to write the programs & design the fixtures, order material, make the fixtures, run-off the parts, etc. Put a reasonable hourly figure on the time, and quote it. Same as any other business that does turn key machine tool projects for a living.
If they balk at the price, remind them that your programs, fixtures, toolholders, etc are not "new & un-tested," but rather have already been proven, and guaranteed to work in your facility, with your people. Remember yourself, that you will be losing any revenue from running their parts in the future. And the equipment to run other jobs, etc... (I'm sure you've already thought of that and have your reasons for considering this, just don't forget that fact going forward.) For these reason alones, you should consider a premium for yourself...
Make sure they understand that once they assume responsibility for taking over, that you are cleared of any responsibility. This is where it could get messy, as now they'll have every excuse imaginable to point the finger at you if things don't go perfect. Even if they have Joe-Blow running the parts, checking critical dimensions with beat-up calipers, loading stock that hasn't been de-burred, etc...
I'm not a lawyer, but I'd be consulting one, thinking of having them sign a waiver clearing you of any responsibility once they accept the project. Put in clear, measurable, terms/objectives that cannot be easily disputed, designed to guarantee their satisfaction & acceptance of responsibility.
That may sound ridiculous, but I can just visually imagine the excuses coming out of the woodwork at the 11th hour, when they're complaining that they don't have good parts because of ____________________________________ . <------ Insert crazy, irrational excuse there.
(I have the words from the book Winning Through Intimidation screaming loudly in my head right now as I read about this "proposal" and all the possibilities. On an aside, ewlsey, I'd recommend it - as it was recommended to me by PM member Oldwrench...)
If you can come up with a worthwhile** number, that you can rationalize with facts & sound reason, and think you can get them to close the deal without going flaky on the final payment, then do it.
All the best.
** Worthwhile to YOU - That doesn't mean it has to be a "bargain" to them, but only "fair" to both of you...