The cost to renovate would depend on what precisely they want to do with the renovation. Cleaning the place up but leaving the floor plan identical would, of course, be much cheaper than knocking down some walls and throwing up new walls and so on.
As for statue value, I’d expect it to range widely based on craftsmanship, material, gem-encrusting, and so on, but anywhere between 100 and 10,000 gp (or more for insane things) would not surprise me. For time, though, that one can actually be answered! A statue is an item that would need to be crafted, and it would follow the production rules for the Art or Craft proficiency/stronghold building/building all other sorts of stuff.
A Master Artist working with 2 journeymen and 4 apprentices can produce 120 gp worth of art per month of work (ACKS Core page 58). So with one team working on it (which I personally would say is the limit, unless you want the statue to be built in parts and assembled on-site), it will take GP Cost/120 months.