I have a beautiful fretless Warwick Thumb bass that never gets played.....mainly cos there is very little call for fretless bass these days!
It was customised form me as an 18th Birthday present from my Mum - it had 18 in roman numerals engraved at the 12th fret and blue LED's installed on the side of the neck and on the roman numeral....For that reason it will never be sold, even if it doesn't ever get played again!