The spare parts list for the last contact of the war "C7218" gives the price of the front fork assembly as £8 0s 0d, £2,200 is only about an 8% per year return on that price in 70 years.
Better than the bank but he would have done much better buying a "picaso".
Are they worth that much? I don't think so, but he does have a best offer option so maybe he would accept a lot less?
However, £2200 (plus duty, plus VAT, plus international shipping charge) might not be the end of your problems...Although the bushes in my new forks are bang on size the spindles on two of the links are outside of the laid down tolerance and are going to need attention before I'm happy with them......
I also suspect that once you have ridden a few miles on your 'new' forks they won't add that much to the market price of your M20....
Russells still have new crank cases I believe for £300..That seems very reasonable ..Ian