Why not just use the number stamps like they do at Kona?
How much do one of those stamps cost?
I could not find something like that online- or what to call it. If you search big number stamps, you get kid stamps. I'm sure an office supply store? If anyone knows what these are, post a link or say where to get them.
I googled "ruber ink single number stamp" and got results for custom stamps. Something 3x1 inch would cost around $12. But I'm not sure if you could get something cheaper because the design you are looking for is just a simple number. I'm sure the price is assuming you will have a custom design more like art work.
Is it a rolling stamp, or would you have to buy a stamp for all 0-9 ??