I would like to purchase prints of historical portraits, namely
of 16th Century reformers, Martin Luther, John Calvin.

Hi there,

I believe that I've found just what you're looking for! Historical
portraits of both Martin Luther and John Calvin can be found at the
website historicprints.com, in their Heroes of the Faith section
(http://www.historicprints.com/heroes.htm). They offer 11" x 14"
colour prints of both the men you were looking for, plus prints of
quite a few other historical figures. They are based in Maryland and
to order you can call, fax, email, or use their online ordering form.

I hope this is what you were looking for. If you have any questions,
feel free to ask.
-Deadlychiapet-ga

Search terms used:
historical prints
historical prints "Martin Luther" -King
historical portrait prints
"john calvin" prints