Frank Lloyd Wright National Reciprocal Sites Membership Program [$100]

7 of 8 components are included amongst several other works by FLW. The Herbert and Katherine Jacobs House (Madison, WI) is private and only viewable from the residential street sidewalk.

Taliesin (Spring Green, WI) $42
Taliesin West (Scottsdale, AZ) $39
Fallingwater (Mill Run, PA) $35
The Guggenheim Museum (Central Park - New York City, NY) $25
Robie House (Hyde Park - Chicago, IL) $20
Unity Temple (Oak Park - Chicago IL) $15
Hollyhock House (East Hollywood - Los Angeles, CA) $7

Collectively, the lowest price available for tours (guided or self-guided) that include interiors of these 7 components of the Frank Lloyd Wright Buildings world heritage site is $183. There are off course many more expensive tour options. So, one intrepid traveller can procure a decent amount of savings if you can visit all 7 components in 6 American states within a years time!

Do you know any other Reciprocal Programs specifically for serial WHS?

It could become a connection.

I'm not sure if this is quite what you're asking, and it is certainly not WHS focused, but looking at the UK English Heritage (which manages Stonehenge and much of Hadrian's Wall), Historic Scotland (Edinburgh Castle, Antonine Wall and Neolitic Orkney) and Cadw (Gwynedd Castles and Blaenavon Ironworks) all have reciprocal visiting rights for members. English Heritage separately has the same with OPW (Bru na Boinne and Sceilg Mhicil) in Ireland.

The National Trust (the most interesting Cornish Mining sites, Avebury, Fountains Abbey, chunks of Jurassic Coast and Lake District, Penrhyn Castle in Welsh Slate Mining Landscape, Giant's Causeway) has reciprocal rights not only with National Trust Scotland (St Kilda, some interesting locations in Edinburgh) but also other INTO members (a quick scan suggests Kromeriz in Czechia, Old Government House in Sydney and a few TWHS like Heart's Content in Canada and the Villa Gregoriana in Italy).

The platinum card in this area may well be Heritage New Zealand. No WHS properties of their own but free access to the INTO properties above, plus also English Heritage (not Historic Scotland, Cadw or OPW from what I can see though).

I don't quite see the difference to a Parks Canada / America the Beautiful pass that lets you visit dozens of locations for free within a year. Israel Pass is another one that comes to mind. So basically the connection is "annual pass"?

"Annual pass" could be a connection, but I don't think it is the idea (or at least, not enough) when talking about "reciprocal sites". There are lots of single sites (museums, castles...) where you can buy an "annual pass" only for that site.
I guess winterkjm is looking for a group of sites that can be viewed with the same "pass" (annual or daily as well). Am I wrong?

If it was simply "annual pass" that could mean well over 100 connections! Is there a reciprocal program for the 17 Le Corbusier components? This could be possibly useful information for travellers who are trying to visit the majority of a serial WHS that is managed by various entities.