Quote Originally Posted by Flotsam
At 70 cents a pop, buying new cassettes really eats up a lot of the economy of bulk loading. I save my Efke and JandC cassettes and clean the felt well between uses, a post-it note is just tacky enough to grab dust and grit without tearing up the felt.
For the ultra-cheap, you can re-use commercial film cartridges, even if they're not officially reloadable. You've got to unload the film in the original cartridge without opening it, which isn't too hard -- just don't rewind the leader into the cartridge, or use a leader retriever. Alternatively, if you don't shoot enough non-bulk film to supply yourself, you can get empties from the local 1-hour photofinisher. (Some will be weird things taken from single-use cameras, which can be interesting.) To reload these cartridges, rather than attach the film to the spool, you've got to attach your film to the stub of film that sticks out of the cartridge. Use cellophane tape to cover the entire area of attachment, on both sides.

I've not been bulk loading long, but I've tried this method, metal reusable cartridges, and plastic reusable cartridges. Overall, I prefer the metal reusable cartridges, but the reused "single-use" cartridges have certain advantages, such as better availability of DX coding and of course low cost. OTOH, the felt traps aren't as easily cleaned, although I bet the methods described here could be adapted -- you'd just need to temporarily tape the film stub to something to keep it from sliding into the cartridge. Then too, with 1-hour labs willing to hand them over for free, what's the point? Just use 'em once and toss 'em!

Gotta love those $1.50 35 exp rolls of Tri-X.
Or in my case, $1.00 (or less) rolls of (Freestyle rebranded) Ilford Pan F+ or Fomapan 400.