I wouldn't want to buy a ready made full set. The thrill of the chase is most of the fun of it.
The rarest is the Grana. You'll be looking at £8K for a good one, maybe more. The IWC is probably about £5k. The Longines is getting up to £4k now. Best bang for buck is the Cyma as it's a Stainless Steel case, a more contemporary size at about 38mm and a relatively modest price at about £1k.
I'd have put the full set at about £30K. That's before adding the buyer's premium from the auction house.
Here's my full set plus a couple btw