Martin "anything" is worth a lot of $$$ but of the bunch (soprano, concert, tenor & baritone) the baritone ukes tend to be the least in demand and consequently the lowest priced (aside from the style 0 soprano).
On the flip side, a clean martin baritone in excellent original condition can also fetch a premium price too. If you can find one in original condition but not mint you could possibly get a great player uke at a heck of a value.
