The pens cost about $210 for five pens (300 units a pen=1,500 units altogether) and the vial about $110 (1,000 units) so they do cost more per unit. However, the countdown on the expiration date of the pens (noted on the pen...usually sometime in 2013) doesn't start until the first time you put a syringe in it. Therefore, you will be able to use just about every drop of every pen, even if you use a small dose, because going through 300 units will only take a couple months (it took me 34 days to go through my first pen at an approximate dose of 3.75u b.i.d. ). The countdown on the vial's expiration date starts the first time you put a syringe in it and it's very hard to get through 1,000 units before the effectiveness of the insulin just goes downhill, unless you have an acro cat who needs a large dose. No matter how well you treat your insulin (keeping it refrigerated, not in the door of the refrigerator, don't shake it, etc.) it will lose its potency before you use it all up. You may be able to find a pharmacy who will sell you one pen at a time. Here in Las Vegas, I only found two pharmacies who would sell me one pen at a time. One wanted $67 for one pen!!! The other pharmacy, believe it or not, was a Kmart. But not the Kmart closest to my house. I've found out that pharmacies within a chain (all Walgreen's, Rite-Aid, etc.) can make their own rules so you have to call each individual pharmacy to find out if they will sell you an individual pen. Some people have been successful getting a hospital pharmacy to sell them a pen, but all the hospital pharmacies here in Las Vegas will only sell to their hospital patients. Some people also have luck with Sam's Club, Costco, or Target selling them one pen, but they won't do it here. You just have to call around. My vet didn't know about the pens either. Just ask your vet to write a script for the Lantus Solostar pen, but have him give you two scripts, one for the five-pack and one for the individual pen with refills p.r.n. That way, if you can't find a pharmacy who will sell you a single pen, you'll have the script for a five-pack. Some people have been successful buying from Canadian online pharmacies which is half the price for a five-pack of pens than it is here in the States, but you have to decide if you want to take the chance of them shipping it in the summer and them not staying cool. Personally, I'm not going to order that way until the cool weather comes back in the fall, but then I'll have a five-pack that will last me a year!! Geez....I hope my Champers gets to the falls before that!!