Hi i just wrote a ton and hit something and lost it all.. Anyway. Old guitars like Kay , Kallamazoo Slingerland   Epaphone and even Harmony are not so expensive and can have a wonderful sound for slide work. You have to just try some instroments and see what touchs you. Remember that next year you will be hitting the srings differently then you are now. I would recamend getting a brass dunlap slide ( My Faverite) or for a heavier slide try a craftsmen extended socket ( 5/16ths is my size I think)
      On the other hand , I just got my son Sam a wooden bodyed National Resonaphonic and it is amazing. At $1500.00 it will give years of great music and if its not the right guitar for you it is saleable for near what you bought it for ( more if you keep it a few years!) Good guitars are a wonderful investment. They are great to play and mostly just get better. ( Unless you leave them in the hot Attic. Or use them as a weapon in a bar fight. )
    You reallly just have to try some and see what catchs you.
      On finding them : I got a Kay Proffesional (1930's ) at a pawn shop . A Kallamazoo large hole from a vintage collector,. A harmony at a tag sale. Two were under $100.00
          All the best , Guy