A cheap option would be to look at some used cameras that have nightshot capability, that have had the hot mirrors removed. Maxmax typically charges $175 for the conversion, so just add the cost of the camera. Many compacts can be picked up for $20-80 used, and converted, making your total cost well under $300. A list of possible used cameras to look for that they'll convert:
Sony DSC-S30, DSC-F505, DSC-F707. DSC-P51, DSC-P72, DSC-P93, DSC-P150, DSC-P41, DSC-P100, DSC-R1, DSC-F828, DSC-P30, DSC-N1, DSC-N2, DSC-W200, DSC-W300, DSC-980
Fuji F10, F20, F30, F31fd, F40fd, F50, S6000, A400, A500, A900, S9100S, S8000, S6000, S1000fd, J10, J20
Canon Powershot G5, G7, G9. G10, S5-IS, SX10-IS
Panasonic Lumix LX2, LX3, FZ28
Also, if IR/UV capabilities with reduced visible light is most desirable, and visible light isn't as important, Sony manufactured a few cameras with built-in NightShot capability, which is simply IR photography (it can't be used in daylight though without a very dark visible light cutting filter, sold at most camera stores or online)...check the F707, F717, F828, V1, V3, or H9. These were the only still cameras made with built-in full-spectrum capabilities with the flick of a switch. At night or in dark areas (where I'd imagine most ghost hunting is done), you won't even need any filters. And some of these models go back to 2002...finding a used one shouldn't be too hard as they were all pretty good sellers.
(BTW - a quick look on keh.com shows a Sony F707 used in excellent condition for $105...just as an example!)