Hi David,
Sorry to hear about your Dad always a difficult time, my sincere condolences.
However back to the Myford which I am sure was Dad's pride and joy, as far as value its difficult to be precise but it was probably made around the 1960's you can find the number on the lathe bed usually near the headstock and look up the date on the Myford web site.
The machine has a longitudinal travers but not a cross traverse, price is governed by age, condition and whats with the machine. For yours IMO age is good, condition is difficult to ascertain from the photo but it does look good and clean, one downside is it hasn't got a gearbox – not essential by any means but very desirable but so is the machine.
It would probably be worth looking for local ME clubs and contact them or look up SMEE in London and just maybe they will help with valuation?
I would start at a higher price – you can always negotiate from there.
Look at your PM as well — little box flashing at the top of the page
John