I’ve been interested in baritone guitars. A baritone is tuned a perfect fourth lower than standard. You can think of it as a standard guitar with a neck five frets longer.
Why not a seven-string guitar instead? I don’t know. For some reason, I just think I’d prefer a baritone to adding another string.
And I’ve come up with a practical use for a baritone: When the music director has decided to transpose to a lower key, you can effectively “reverse capo” compared to a standard guitar. i.e. Putting a capo on the fourth fret of a baritone is like being able to capo the -1 fret of a standard guitar.
Danelectro seems to be coming out with an affordable one. The Eastwood Sidejack Baritone looks pretty nice. (Unfortunately, there doesn’t seem to be a way to link directly to its page.) The Gretsch Jet Baritone looks interesting too.