PS: If you decide not to buy a laser printer, there are some ways you can make your inkjet-printed wallets more water-resistant. I'll be posting a report on this soon as I'm in the process of testing a bunch of different products/solutions.
I'm slightly curious how well it'd work to do a three-pass print and not a two-pass. ( which makes this even closer to the other project, but... )
Print the front and back in color without the QR codes on some printer [ color laserjet, color inkjet? I wonder how it'd work if those ink could bleed when wet when the QR code couldn't? ], and then print the QR codes on a cheaper black and white laser printer.
This would probably also work for your "super paranoid" option, without having to buy a nice color laserjet and only use it for wallets.
[ However, I imagine the pain this would be to align and calibrate across two different printers ]