Why not year 5 stamp? and seasonal stamp... both are retired and year 5 stamp is REALLY cheap! in addition to the 40 ring of sloth stamps i now i have, ima add a few of those. Why not try to attack those also?
the thing with these stamps is that there are still soooo many out there, whereas snowbunny are unbuyable and are only on tp and are getting less and less
At this point, snowbunnies cant really be too good of an investment... If you can afford to buy 40 (10m nps) the most really you can make is maybe double over a year or so... But Ring of sloth stamps are expected to triple within a month or 2... and money can be made with much less money put in.