Yes I have 2 or 3 PS2 mice and 2 or 3 PS2 keyboards laying around, but generally speaking these are more expensive than their USB counterparts. I know that it is a bit late to mention this but I just noticed this today. If you want a LONG LIFE for this , I think future revisions should at least have USB in addition. 10 years from now PS2 may not be available FOR ANY PRICE. I know that you are trying to preserve this 80's idea but these are just my thoughts.
Dan
@tim1724 you are right " only work with keyboards that can be convinced to speak native PS/2 " I forgot that part.