I say just makers mark and steel type. Since you have input into the designs by the customer, and some are versions of a specific type (unless you both come up with a name and you make more of them so it is not a one off). You could do a sort of business card type thing. I have a few from different makers that have the makers info on one side - logo, email, website, phone number - and then the knife info on the other - steel type, RC, date, handle materials, name if it is their original design/take on a style, specialty things - jewels/inlays/engraving, other special materials - mosaic pins, timascus/zirconium/damasteel etc...
Also I have knives that only have the makers mark (which is fine) but I would prefer the steel type as well.
Also Also, I think some of the business card places still offer an initial lower cost (or free in some cases) bundle for first time customers, where you get a couple hundred cards or so of your design.