i paid like $90 for my loose (green) monster a little over a year ago.
as for rarity goes, i have actually kept track of it mostly last year,
all 4 colors are present in the boxes,
this counts for both the European and American release.
my counting total of which colored versions i have seen most to least last year:
- 5x Orange
- 4x Blue
- 3x Green
- 2x Pink
-------------------------
Collection as of april 29th 2018
- NES Sealed Games Total: 2
- NES NIB/CIB Games Total: 28
- NES Loose Carts Total: 139/366 (incl. label differences)
- NES Manuals Total: 66
- Game Boy Loose Carts Total: 27