I am trying to find my daughter a fairly simple RPN scientific calculator, and have been reduced to bidding on 20-year-old HP calculators on eBay. There isn't anything out there new.
Although, it looks like HP may be launching a algebraic/RPN business calc that looks similar to the HP27S/32S/42S models (Pioneer models), so hopefully a scientific will be next.
http://www.dynatech-taschenrechner.de/produkte/produkt.php?prod=4992
note it has "Umgekehrte polnische Notation"