So I am building an old '71 Triumph Sportster into a daily commuter. It has old, non hook style 26" x 1 3/8" rims; but the new tires need hooked rims in order to inflate to the pressures I want to run. So, I need new rims. I'm not overly keen on running new style 26", mountain bike rims. I'm also OK with running something more modern and not "period correct".
Cannondale SuperX, Santa Cruz Tallboy, Surly Krampus
redxj answered your question. I got three set of wheels with Sun CR-18 in ISO 590mm. You can get them for roughly $30 a piece and then put any of a multitude of tires on them. I use Schwalbe Marathons/38mm wide, but these are more money than the rims. Michelin World Tour is $10-15.
The look is highly polished, with a slight tombstone profile and machined brake surfaces. Could be worse, but not entirely classic.