I see most of the Pennsy Models from USH and MG and sunset at O scale shows. Maybe not all at all shows, but within a year, I have seen 4-5 L1s, 4-5 I1s, some USH K4s, CLW H10s, GEM B6, USH C1, MG C1, Various M1 and M1A, N1 and J1
I also see many of these for sale on EBAY, but I have never dealt that way.
Norm's O Scale, Allegheny Scale models usually have 5-10 pennsy models on their websites or in their ads. They usually have many tables at the March Meet in Lombard IL (Chicago area). American Scale Models (Bill Davis) also has a large variety of stuff that changes rapidly.
The L1s seem to be most available, ie least popular. I1s show up pretty often too, and then probably 3rd are the mountains. K4 are actually probably most available, but are passenger locos.
