Now. I realize that this particular plug number is priced at the high end of typical standard plugs for classic motorcycles — a check on eBay shows these offered for $10-20…each! Even my local NAPA gets $12.30 each w/tax.
My work-around for getting a better deal on spark plugs is to order from Rock Auto (.com) — four of these plugs shipped to Illinois comes to $33.41, or $8.35 per plug. Still not cheap, but beats getting gouged on eBay (and see the note below).
For comparison, the previous generation RC24/26 (1986-87) plugs, NGK DPR9EA-9, are a less expensive plug for whatever reason; I get these in 10-packs from Rock Auto for $2.78 each, shipped, or $3.37 each if purchasing only four plugs. NAPA wants $4 each.
NOTE: If you find these plugs cheaper elsewhere, including Amazon & eBay, beware, there's a thriving counterfeit business in NGK plugs, a good reason to buy from a reputable NGK dealer. Here's one video that may help, and there's others.