So I'm looking to try infrared photography with the school's 4x5 monorail camera and Efke IR820. I'm looking for a good filter to achieve an intense infrared effect. The only problem is that the cheapest one I can find costs $70-300 for an opaque sheet of plastic. Am I going to have to bite that bullet or is there another option? I've been looking at the wratten 87 or 88A and I can't believe how expensive a small sheet of plastic can be.