I don't know how this is missed, but on petandkennelsupply.com website there is no script for Iverhart, unlike the other heart worm prevention products.

It is 10% off for a 6 month supply and includes shipping. I have tried this out and you can order right online, no verification.

Here is what is on their website.
Iverhart Plus
"Now Save 10% off the regular price of $15.50-$26.75
Offer good until July 15th, Order your today
Flavored chewable tabs that contain ivermectin and pyrantel. Dogs love the taste and giving them only tab a month is guaranteed to prevent parasitic infestations and protect your dog not only against heartworm disease but treats and controls common, zoonotic roundworms and hookworms.
No prescription needed, comparable to Heartgard."