there are several companies and even do it yourself web site for modification and removal of the IR filter. In astro-photography, it is common to see guys with modified IR filter removed cameras so that you can pick up the light form nebulae better. Below is one link for a company i have never used but was once recommended to me:
http://www.hapg.org/camera%20mods.htm As you can see, sometimes people will have a specific wavelength of filter replaced, or you can lave the IR filter off completely. I think if you contact these people and let me know your needs, they or others can fix you up.
Now the reason I suggest this, even though you need it done "on the cheap" is because I have talked to people who have don it themselves, and they have, in thier own words, "mucked it up".
However, if you are feeling brave, here is a do-it-yourself web site:
http://astrosurf.com/buil/d70/ircut.htm There are other web sites for do-it-yourself, but IMO, all equally as scary.
I know you need to save money, but even with a point and shoot, it's easy to mess it up.
Now the other option - a lot of us used to use webcams on telescopes with the IR filter removed. Some still do. It is often easy to take out the IR filter from a webcam, but you need it connected to a computer (usually via USB), and I am not sure a webcam has the resolution you need. But as for cheap, heck, used webcam at a flea market or off craigslist, it's about as dirt cheap as you get.
to find a website that describes how to do it, just google "webcam astronomy" and you'll find plenty of do-it-yourself.
good luck
