Just don't special order some horses.
Picked up some AB Clibanarii years ago on ebay that came without horses.
Called up and got a quote a while back of .75 each for some Battle Honors horses from OG15.
Placed an order in December for some other OG15 minis and asked them to add 19 of those horses to it so I wouldn't have pay additional shipping by ordering the horses separately. Since they don't have a way to add those to the cart directly had to get a separate invoice. When I got the invoice it was for 27.00 – 1.42 per horse. A pack of 4 Battle Honors Clibanarii is 5.00 or 1.25 each for horse and rider. Plus if I had added 4 packs of clibanarii to the rest of the order with the sale going on I'd have gotten a 30 percent discount.
Since I needed the horses and had placed the order I didn't cancel.
Sadly when the order arrived OG15 had sent me armored cataphract horses instead of the barded clibanarii horses.
Rather than just send them back I contacted OG15 and said I'd just order 4 packs of cataphracts if they would swap in the barded horses and not charge me shipping. They agreed. Rather than send a special invoice I was instructed to just place the order through the website. I noted that that would automatically include shipping at which point I was told that if so the shipping would be refunded.
I got the cataphracts with barded horses. Never got the shipping refund. After a couple of emails and phone calls I finally was able to get hold of them at which point I settled for some hoplite shields.
Part of the reason I didn't take advantage of their most recent sale – having only so much money to spend on minis I have other figures I have been wanting to get from other sources and will take care of those wants before going back to OG15 for more of their items.
OG15 does well enough at filling standard orders and has thrown in chariot wheels (missing on a FOG army picked up off TMP) and some other items gratis on previous orders. They also dealt well with a missing rider from a pack of Ottonian Cavalry. They are extremely hard to contact if there is a problem and do not answer emails consistently or return phone messages.
P.S. As a matter of curiosity I contacted AB Figures in Australia and their price for the horses would have been 0.75 Australian (about 2/3s the cost of horse and rider). With shipping it would still have cost less to get the horses from them.
P.P.S. As to the price of horses alone, Alternative Armies/15mm UK runs 30p, or half the cost of horse and rider. Donnington is 45p or 2/3. QRS has packs of 8 horse for the same price as a pack of 8 infantry.