The British printer Barnard & Westwood was responsible for Harry and Meghan's wedding invitations, but declined to comment on their price.

Simon estimates that high-end stationery fit for royals could cost £25 ($34) a set, which would include the invitation, stamps, thank you cards and a calligrapher to address the envelopes.

That would put stationery costs for 600 guests around £15,000 ($20,300).

The royal couple also invited 1,200 members of the public, who will share in the festivities from the grounds of Windsor Castle. If they received the same caliber of invitations, that could add another £30,000 ($40,700) to the bill.