though if you want to buy something specifically for the job..

a perennial favourite for slide blues players are Danelectro 6 strings with the magic blues power of lipstick pickups..
[full range of sounds from clear chiming to gnarly snarly..]
http://www.provide.net/~cfh/dano.html

an origional 50's or 60's U2
or double cut-away [the Jimmy Page favourite..]
if you can find one in good shape you can afford

or a much more affordable and better made recent Korean reissue..
now out of production, so prices fell dramatically
but are now starting to rise again as collectors move in on
the mint condition ones for sale on ebay..