I asked the Etsy vendor how much the caps would be and how to submit my custom image. Here's his response:
"Hello,
Thank you for your inquiry.
Price:
Single keycaps (1 - 21 pcs): $28.50 + $1.50 for each pcs. Gray keycap requires additional charge $0.50.
Shipping cost:
The item price is $50 and less: $3
The item price is over $50, or if you wish tracking: $7
Printing image:
Please submit PNG or JPEG file. The size is:
Top: 283 x 319 px
Front: 354 x 295 px. Actual printable size is trapezoid, top side length is 283 px.
Keycap color:
Please specify color of keycaps. Beige and gray are in stock.
Thank you!
"
So, if we get a group buy for >71 caps, the per cap price is between $1.50 and $2.00.
Who's interested? Also, how does one organize a group buy?