I have a 2.5 LB NOS bottle for sale. Bought it 1.5 yrs ago and never used it, its got the N20 in it still from when I filled it from a 10 lb bottle lol. Has standard -4 fitting.

I seem to recall paying like 180 bucks for this thing after shipping and stuff from summit.

Too lazy to look it up on summit so I'm gonna say $125 for it.
PM me if interested. Thing is just like brand new.