30 35mm cameras is a lot. And I get that film and developing isn't cheap. You can minimize costs by using B&W films like Kentmere, developing the negatives at home, and scanning them yourself...
Instead, why not sell off some of your cameras and use the proceeds to pay for film and developing? Selling 15 cameras at $50 each nets you $750 which will buy a lot of Kentmere 400 ($5/roll at B&H with free delivery for orders over $49) and commercial developing. Even more if you buy what you need to develop the negatives at home (tanks and chemistry would be about $100 and develop dozens of rolls).
I'd sell off all but 4 or 5 favorites and set the proceeds aside to fund the consumable part of the hobby. With some smart shopping and more judicious selection of shots, you should be able to stay in the game for a few years.
ETA:
I just checked B&H for prices. Kentmere 400 is a bit more than I remembered and is now $6.99/roll. However, 20 rolls of that, a Patternson dev tank and reels, a bottle of LegacyPro L110 (identical to HC-110), and Ilford Rapid Fixer, with tax and free shipping, is $217. You'll need bottles for mixed chemistry, but I've just reused drinking water bottles. That would give you enough for a year or more of shooting if you're choosy about your shots. A couple years ago I bought 30 rolls of soon-to-expire Fuji Acros II from Adorama at $5.99/roll. I'm still shooting from that stash (I also use other films, hence my slow consumption). I think I have 12 or so rolls left.
Chris