Before I first posted I tried emailing both Bare Boxer and Detour Zone, asking about availability and to be put on an email list to be notified when available — no reply from either one so far. That's why I posted the question. I guess I could try phoning.
I appreciate the suggestions for alternatives, but none have been either smaller or lighter than Contender. As far as I know, Contender is the smallest and lightest approved canister. I doubt any will get smaller — as Bob G said, there is a lower bound on size, determined by what a bear can get its jaws around. I could easily imagine a future product being lighter than Contender, though — provided there is enough market for someone to develop the product.
I would not call Contender "ultralight", but it gets closer to that than any other bear canister does.
I'm not worried about the small capacity of Contender, or the fact that its weight/space is less efficient than the others. It is fine for a weekend and I already have a Bearikade Weekender if I want more capacity. What I *am* trying to do is downsize my pack, and Contender would help.
Contender: 7.4" dia x 8.0" long 1.6 lbs (25.6 oz) 275 cu in $39 (Detour Gear Zone) $60 (mfr)
BV 450: 8.7" dia x 8.3" long 2# 1 oz (33 oz) 440 cu in $65 (Amazon)
Scout: 9" dia x 8" long 1# 12 oz (28 oz) 500 cu in $195
BTW: has yellow-yellow opened a BV450 yet?
Curiosity question: do any of these bear canisters work with polar bears?