I saw the acoustic guitarist Gordon Giltrap perform in Dolan's at the weekend. Some nice tunes of course, but I was rather taken with the baritone guitar he whipped out for a few numbers. I said to my neighbour 'custom job!' You just don't see these guys hanging in music shops.
The baritone looks like normal guitar but is tuned a fourth or fifth lower, i.e. to A or B. It needs a longer scale and a stronger neck, but it has a huge sound with great sustain.
When I got home, I hit eBay immediately but found no listings (except some electric models, mainly used by the nose-bleed metal crowd). So I thought I'd let you know the results of some later intense searching.
The wonderful George Lowden (Northern Ireland) made a baritone model last year and will make you a custom version on request for an extra £250.
Chris Larkin (Ireland) made one for Tim Van Roy, now called the TVR Baritone. No specific prices but his acoustics are 'from' €2,150, so I'd guess about €2,600.
Tacoma (a subsidiary of Fender, from Washington, USA) makes one for €1,975.36.
Avante (Korea) makes a slick pointy one! Only $519 with electronics. This is an ideal starter model to find out if you actually like the darn things.
Regarding baritones in general, something in me whispers 'toy,' if only because of the rarity of the instrument. If it was useful they'd all be making them. Think of the evil that is the 'guitar banjo.' O dear Lord!