Link 1: only been up for 11 hours, already has an offer of a N&B tippler's (13-16) plus "lots of sweets".

Link 2: offer of p. fetti stove pipe (19-24) retracted because he sold it (for another N&B batters (mint))

Link 3: only offer is of 17 keys but that already beats the current range (and this guy is slow to bump trades it seems)

Link 4: closed trade, had an offer of 1 bud but it looks like the guy bought another hat. Rejected 15 pure, c/o'd 16 (two weeks ago)

The range suggested comes from the completed deal with the stove pipe (minus some, because he paid in unusuals), and considering the whole discontinued thing, there are still 5 on the market and only 3 have offers. I do suspect the range might change as we get nearer to the discontinueing but I offer this as a starting point.