Having had some experience with replacing teak decks I would caution a very thorough inspection of the boat if the decks are screwed down.
Obviously spongy deck areas are a major warning sign.
I am not sure how Monk's are put together, however a common build method for these style of boats was using small blocks of hardwood encased between fibreglass as the deck support, then laying down the teak on top and using screws to secure through the top of the fibreglass. As the decks twist the screws work loose and water percolates through. Over years this turns those hardwood blocks to mush. That's where the real problem and expense lays.
Having said that, not all boats had wooden blocks, some had foam or other types of non pervious material. Even within the same brands the building technique differed. As an example, we have an Island Gypsy 36' and 'Bruce K' has one as well. Our boat had the wooden blocks and Bruce's didn't, similar age, different build technique. Go figure.
Teak decks are great, as has been already said, but there may well be a cost factor to that.