Talking about the cost is nonsense it you don't know what is required to be done.
If the decks are laid (thick) teak then it may be that all is needed is to refasten and recaulk the deck, with replacement of any bad planks and finally sanding flat; I did this with Carina while in
Turkey, with the help of a local. It is a bit of effort but not a huge job. In this case the teak remained well bonded to the underlying
plywood and there were no
leaks or
rot. In another decade or two I will need to replace the teak; I love the look and the grip but given the state of the teak market I will be glassing instead of putting down teak again. Also much cooler on the feet and down below.
If the teak is at the end of life then I think the best solution is remove and replace with glass, unless you are rolling in
money. Even then, all of the screw holes are potential
leaks, and on many boats you can strike the word "potential". With teak over glass every one of those holes should be opened up to clean, hard composite (no loose fibers) and then properly patched before any new deck is put down. Finally filling and fairing, with paint and non-skid, will yield a good, low-maintenance deck. It is a big job but the only way to prevent leaks. Putting a heavy, thick teak down on top of those
repairs is an alternative; there were several shops in
Turkey that had the teak and did a beautiful job. Aside from the initial cost there will be the ongoing
maintenance of course.
Newer boats have teak decks pre-assembled and are vacuum-bagged onto the glass deck. They look great, have no screw holes, and are easy to replace if the deck pieces can be sourced from the factory. Because they are thin the expected life is shorter but otherwise is a very good solution.
The costs for these alternatives vary greatly so you need to know which direction you want to go first. The real potential joker is the possibility of damage, potentially extensive, that is not visible. In teak over
plywood the plywood can develop
rot, although not a lot of boats are built this way. More typically the teak will be over a balsa-cored glass deck. Balsa is rot prone, so any leaking screws can cause damage. This is often indicated by a soft deck (it yields slightly when walked upon, over the area of rot). Obviously a really picky
survey is needed to determine the extent of the damage, but there will still be the possibility of undiscovered rot. If the teak is over a solid glass deck then the risk is small for other damage.
In today's market it is almost certainly better to buy a boat that doesn't have deck issues to begin with, unless you are a competent
DIY person with a lot of time on your hands.
Buying a fixer-upper and paying professionals to bring her up to snuff just about never is cheaper than
buying a boat in good shape. If
money is an issue then look for a smaller boat that is in good shape, rather than a larger one with problems. No one "needs" a 50' boat for a couple to
cruise.
Greg