There were three things that brought my into thinking that passive house can actually be affordable. There is the Minnesota passive house that is at the Minnesota State Fair, talked with the guys there about the costs and the additional costs of the passive elements are partially offset by not installing a standard HVAC setup and further by the utility costs. They don't really have a good web site with info and pictures or I'd try to link it, sorry.
The second was the 100k house project, they built affordable low energy houses and then eventually went all in for a passive house, it is a great read to show the extra steps needed to reach passive. They do show lots of details like installing a thick plastic barrier to prevent air from below the slab from interfering with the 50 pascals, lots of things I didn't think of.
The final, and my favorite is the CLAM affordable passive house. I watch this video and it shows a lot of detail of what was done to seal up the structure (11CFM at 40pascals prior to windows) and .35ach50 after full construction. This one made me realize that you don't need a concrete stucco or metal clad building to seal air and brought plenty of ideas together for me in case I ever build a new house myself.
Even if you did slink to a 1.7ACH50, that's still very good. There is a Duluth, MN house project that didn't meet the Passivehaus standard because their ACH was at 1 but the house is still effectively passive, even in a climate that has a design temp around the -20f region that has plenty of wind from Lake Superior.
The ACH standard seems tough to meet and I see the limits myself for payoff periods with my own retrofit. It seems that the airsealing that I've been able to do was cheap and anything that I can't do involving tearing down walls would cost more than what I could reasonably make back. I find that Passivhaus standard seems to always be focused on reducing the heating need of a house and adds more windows than would probably be needed which creates a high cooling load unless the proper overhand is built in, which I rarely see being done. For my house think that blocking most of the light in the summer will reduce my energy use the most over doing anything else that I haven't done yet, more so than heating costs with my current equipment setup. Likely not if I swapped out my air conditioner with a more efficient one but the swapout of the air conditioner and furnace is I can't see ever paying off because it would take a very long time to rack up even a $7000 energy bill at this point. $300 of insulation, easy to make that pay itself off.