Seems like a good price depending on condition at $150, so anything under that would be a nice deal.
Have you used film in the past? It takes a lot more dedication IMO and you'll need a good scanner and a lab you can trust. Over time, you might wish you had just paid the upfront cost for a 5D classic.
you could sell the 350D, 18-55, and the 50 1.8 and put down about $300-400 for a used 5D. by the time you buy a year's worth of film, develop, scan, and process the images, you might find you've spent more than that.
Even more likely, you might find yourself wanting to sell the 7D
Whether it's worth it or not is ultimately up to you, but if you are going to use it in anything but daylight, I would stay away from the film camera. I have a Nikon FM and an EM (manual focus film SLRs) and I use them for landscape shots and for outdoor shots where I want a thin DoF for portraits, but other than that, they stay in the bag. Also, I paid less than $150 for all my film equipment combined (2 bodies, 4 lenses)
You could always try it and sell it if you don't like it. It's not going down in value after this long