There are RIP programs out there that aren't nearly as pricey as FASTRip. You will need the RIP software to print half-tones, so if you're not doing any of that, then you don't have to buy anything just yet. Murphy's law dictates, however, that as soon as you don't buy what you need, someone will come to you with an order that requires what you didn't buy. There are a lot of threads dedicated to RIPs, and I think there are even some available for free, or close to it anyway.
You can also use ghostscript for halftones without buying a RIP.
I haven't done so yet but currently stick to straight spot colors and print my films directly from CorelDraw onto my Epson 1400 using the color seperations tab in the print dialog box.
Check out AccuRip. It's cheaper than most and you can download a free trial version. We use it with some Epson R1800's and it works really well. It easily can control the amount of ink laid on the films for nice dark prints.
Along with Ghostscript, which is what I use to output halftones and jobs from Illustrator where I'm specifying overprinting to get trapping, you can output halftones out of Photoshop by converting the mode to grayscale, then to bitmap, and select halftone screen in the "Method/Use:" button, then specify your linescreen, dot shape and angle in the subsequent dialog boxes.
The one real advantage of using a RIP with an Epson printer is that the RIP can control the amount of ink that's output by the printhead nozzles. With printers like the HP9800 (which is what I use along with Ghostscript) you have to go through the print settings and try and come up with a combination that works, outputting films dark enough to get good stencils. It is doable, though.
Is rip software nec for printing films? 
