I have to agree with the others that that's a lot of insulin! Please make sure your caretaker has instructions for what to do in case of hypoglyvermia
http://felinediabetes.com/FDMB/viewtopic.php?f=14&t=1122, and make sure you have the tools easily available for them
http://felinediabetes.com/FDMB/viewtopic.php?f=14&t=2354.
Also, learning how to home-test your cat's blood sugar level will save you money (no need for fructosamine tests) and give you peace of mind (you gain a lot of knowledge and control over your cat's diabetes). You can learn how to home-test here
http://felinediabetes.com/FDMB/viewtopic.php?f=14&t=287.
The closest replacements for PZI-Vet are having a PZI insulin made by a compounding pharmacy (there may well be one in your area; check your phone book for compounding pharmacies; alternatively, a lot of folks are using a PZI made by a compounding pharmacy called BCP in Texas), or ProZinc which is being trumpeted as the Idexx-PZI replacement insulin by it's manufacturer (BIV, who bought the rights to PZI-Vet from Idexx).
If you absolutely must have PZI-Vet, I can't offer you any direct help; the only place that I knew that was still carrying it (Drs Foster and Smith) has switched to ProZinc.
I did contact BIV last summer. Please note that this was *before* ProZinc came on the market. Whether BIV still has their hotline open, whether they're still tracking PZI-Vet or have thrown all their supplies in the garbage, I don't know. When I contacted them last summer, they had a PZI-Vet distributor hotline at 866-638-2226, and they were keeping track of which distributors still had supplies of PZI-Vet available. They have (had?) five main companies handling distribution of PZI-Vet; at least one (Butler) has run out. The other four were MWI, Webster, Columbus Serum, and Professional Vet Products (PVP). You can try calling BIV's PZI-Vet distributor information line to get an updated status on which distributors still have PZI-Vet in stock. Like I said, I've no idea whether the number still works or it's still in stock.
If it *is* available from one or more of the distributors, you might want to ask your vet which supply company sells them their medical stuff, and whether they have alternate distributors they use -- it might be one of the companies which still have it in stock. (Most vets get their supplies from one main company, but may have accounts with other companies for things they need less regularly or as a back-up source, but these alternate suppliers are not
necessarily a place that they'll think of checking with when looking for something.)
Alternately, some states allow your vet to call in a prescription to another vet. For example, I'm currently in New Jersey but, if I run out of many (not all) medications, I can call my vet in Maryland and have her fax a prescription to a vet up here who has the medication in stock and the NJ vet can dispense it to me. Not sure what the regulations are where you live. However, if you live in an area where that's legal, and your vet doesn't have a relationship with one of the distributors, you might call one of the distributors directly and explain that you're trying to find a company that still has PZI-Vet in stock, one that's either local to your area or will sell over the internet. Once you've found and confirmed a source that will sell you PZI-Vet, call your vet with the phone/fax info and have your vet send over a prescription for the other company to sell some PZI-Vet for you.