A good used one will cost quite a bit less than a repair BUT, you need to make allowances for painting and prep pluus the shipping which will cost a fortune.
As long as you cant see broken glass in the bottom of the unit, you most likely have a burned out transformer (ballast). Until you can replace the ballast, disconnect the power plug that is behind the interior trim on the trunk lid and replace the burned out fuses so you will have tail and...
2 47' Mercs
1 75 Merc
1 73 Merc Capri
1 74 Merc 3 Capri
3 46-47 Fords
1 40 Ford
3 T-Birds **I forgot to count Supercoupes - there were 7 of those..
3 LTD's
1 54 Customline
1 51 Lincoln Capri
1 71 Lincoln Town Car
2 Mark VII LSC's
13 Mark VIII's
Total of 33 so far. ** SC's raise my total...
If what you want is a cassette player that controls the trunk mounted changer, look for the factory unit that says "CD" just to the right of the cassette loading hole. They are common and easy to find.