You will not need 10K to pull the plumbing and destinkafy it! If what you get is anything like my 30'r, you will need about 15' of sewer hose, $2-3 ft, head $125-500 depending upon type, bowl size etc. The best bang for buck is a raratran phII, IIRC I paid $300 for a house sized bowl, a boat bowl, smaller is about 20-50 less. Spouse's are happier with a bigger bowl! You can do this in a day by youself. Now if you need to replace the tank.....figure a few more $$.
Cushions depending upon the quanitity, fabric, do you need foam, are you having someone else do it, figure 2000-15K from a cover only you do it yourself, to they do everything. I was around 10K for 18 cushions, some matching pillows etc. Wife went full bore with piping, buttons, formed foam etc. Probably could have been done by some one else for as little as 6-7K.
I ended up redoing the foam back vinyl on the hull and top, took about 40-60 hrs, 2-3G in materials. along with another 20-30 hrs varnishing everything too. My 85, was easy to pull things out, take home and do in the garage.
I did this one room if you will at a time. Sailed in the meant time. Even the new instruments were 3G including labor on this one. I was not climbing a mast to install an anemometer, fishing the wires thru etc.
You may find 10K for a refit to be on the low side, depending upon the refitting you do. I also have not gone into the cost to redo the lines, or sails. This is a 30' boat mind you!
This took me about 3 yrs to do everything. I still find a few things to do......
here is a link to how I did the aft berth area, with alink at the bottom to the head area
Then same site, but a link to a GOB article on the boat, with new cushions etc.