There really is not that much stock still out there. Any online site that has a stock counter only show a few models of each about with alot of sites fully sold out. All the 141/181s are long gone, 201 is gone, all of the orange roof IE Mk2s are gone. 111,112 and 113 are gone. I can only see 1 site with 111 in stock and they just have 1 of it. There are not too many 071s left. The 201s are not too popular from the looks of things.
I reckon PM could do another run of 141/181s and they would sell out provided they match the quality of the existing models, same with another run of Mk2 EGVs it would save having to get the ST EGVs sprayed/tippexed.