You may want to clarify what you want to play. A resonator is a special guitar using an aluminum cone for amplification. A slide guitar is any guitar that you use a slide for your left hand.
Any guitar can be set up for slide playing using an inexpensive nut extender.
An actual resonator can be somewhat expensive. The best inexpensive one that I have was made by Republic guitars. I think I paid about $400 for it and it plays and sounds very good.
Hope that helps