It is difficult to give any estimate without knowing exactly what is involved, nor the costs in your country. It depends how extensive any waterlogging is and the extent of any rot. It may be possible to dry it and inject resin.
As a couple of examples a new teak deck on a 37 was estimated at 14000 NZ dollars, while a "new deck" on a similar sized boat where there had been bad leaks on a teak deck so there was some rot locatable other than in the core was 25,000.
A shipwright commented that after 8 years with teak you could expect problems. Those I have looked at suggest a life of perhaps 22-30 years before the teak is thin enough so most of the screws are near proud. In most cases the caulking has had gaps suggesting leaks, so this job needs to be attended to fairly often. If the teak needs replacing I suspect one would just go to fibreglass.
As a very rough estimate on doing it yourself based on reading not doing I would say 200 hours plus say 4000 materials.
With an older boat of that size as a rule of thumb you could reckon on an average 10% of cost pa in maintenance. It varies quiet a bit depending on big ticket items like motors sails rigging
rewiring etc and you can spend big money getting it up to scratch in the first place which really should be thought of as deferred purchase price. Obviously you can save on labour but equipment is expensive regardless of size and boat cost though much of it you may not need for your purposes.