Boutique wheels are a non-cv invention (if we dont count Roval and 1st gen Shamals/Cosmics as CV), so all combinations of hubs, spokes and rims are possible and were common. Thats why not looking at individual components doesnt make terrible much sense to me

Look for some wheels with Mavic Argent 7 or OR 7 rims (265g), or Nisi Pista (227g) but bring a nipple spanner, you'll need it. lightest useable rims üpossibly are Mavic 330s.
http://www.rouesartisanales.com/article-645694.html

or, if you want to throw the wheels on something more vintage, look for Scheerens.