So it's either the black dial CR5110 or white dial CR5111 Monza that you have there. Not sure if it comes with the original strap, but that bracelet is not original. I think for a full set (box, papers and strap) you should be looking at spending a maximum of EUR 3,500.
For this piece, as suggested already you'll have to send it over for a full service plus parts change which will add to your cost. I suppose you can keep an upper limit of EUR 2,750 inc. commission as your purchase price, beyond which time it would be unreasonable to buy the watch and get it repaired