I've got all of these except for C1-4B. From what I can tell it seems to be the most scarce of the bunch, at least on eBay. As for the droids I have? They're nice - the paint deco on S3-R9 and JB-9 are fantastic! But with the BB droids there is all of one point of articulation and the weeble-wobbling action feature. I don't know that collectors are getting tremendous value here, aside from the whole Disney playing on the whole blind box phenomenon that's hot in the toy business right now.
Do you have any extras to trade? I'm hoping to score some more of these, but sounds like they're currently out of stock.
$15 is a little steep for these droids, I'll admit. The droid itself should probably be more like $6-7 with today's prices. I'm willing to bump that up to $10 with the crate it comes in - those are almost as appealing as the droid for me. Add in that the bases connect and they double as a figure stand and have a sticker - I'll bite for a few more bucks. So if these were $12ish at retail, I'd expect to pay the Disney Park markup of $15 for them. I think the build-a-droid figures were $13 or 2 for $20, so not too far off the mark from those either.
For me, $90 retail or a little further over $100 to get a set of 6 with crates is tolerable. If these were a set of 12 and I was looking at $200 just for 12 random crates that could contain doubles, then I'm probably out, but I'm still in the game for now.