Read any article about a major session player and they'll eventually be asked about their vast collection of specialty intruments - baritones, ukulele, quintos, ouds, ocatve mandolins, mandocellos, etc. Many even have standard guitars in non-standard tunings that can be grabbed and tried at moment's notice.
It'd be nice to have a collection like that even if you were not a session guy in the studio scene, but your OWN session guy in your bedroom studio scene. And with a little creativity and not much money, you can.
My first foray into what I call fauxtique guitars was putting the octave/unison set of strings from a 12-string guitar set on a beater 6-string that I was not really playing much anymore. It just didn't sound very good and after leaving it in a freezing cold truck and taking it into a warm club, the finish cracked and it was pretty ugly to look at, too.
The result of using those strings is the so-called "Nashville Tuning", and octave higher E, A, D and G strings, and standard B and high E strings. This guitar, especially when capoed to bring the pitch up even higher, works great when I want that "tuned hi-hat" sound or when doubling an existing acoustic part. It does not have to be a hi-fi sound when the part is going to be textural and not featured, so even boxy and marginal-sounding insruments can be made to work. Cheap guitars to the rescue!
Another option is converting an electric 6-string to a baritone. Buy the heaviest gauge strings you can that will fit through the tuning pegs without alteration and tune it down as low as it will go. B-to-B is the standard baritone tuning, but who says you can't go C-to-C or D-to-D?
Backpacker guitars are cheap and I've seen some for as little as $50. The tiny body has a thin and ancient tone, nothing like a full-bodied guitar, and with a set of Silk and Steel or Nylon ball end strings, you can open tune to the key of the song and add some interesting textures to your songs. Capoed up, these guitars can sound like ukes and mandolins if played in similar fashions.
Next time you're in a pawn shop, grab a $30 beater and convert it into something it wasn't meant to be. If nothing else, you might get some inspiration and take your new song to places it would not have gone if you would have used the same old tools.