The Doxy "shortage" is the bane of my existence. As best I can tell, the manufacturers are telling the FDA that the "shortage" is due to unusually high demand. I found a 10k SEC filing from one of the generic drug makers reporting record profits last year, due to Doxy prices. Draw your own conclusions.
We are dealing with this all.the.time in rescue in the Deep South, as a relatively high dose of Doxy for 30 days is part of heartworm treatment. I've spent many, many hours researching doxy prices. You will not find the $4 or $11 Doxy anywhere -- that era appears to be dead. You may be able to get it for a lot less than you are currently paying though, if you are diligent in chasing the best deals.
WAG dropped Doxycycline Hyclate (the kind that has the shortage) from their RX plan. It was on it a few months ago, but as of right now, the 100mg tabs are not. (I think 20mg might be but that's useless when a dog needs 300mg in a single dose.) The drug on the PDF Mikko linked to is different (Doxycyline Monohydrate)--I don't know what it is, but it's not what gets prescribed for my dogs. I don't know whether they can be substituted -- that's a question for a vet. RA still has Doxy Hycl. it on their plan, but the price isn't dirt cheap -- closer to $1 pill, if I remember correctly.
Here's what I've found:
1. Start with GoodRX.com -- you enter the name of the drug, and then on the right side of the page for that drug, you enter the quantity desired (e.g., 180 tablets of 100 mg). It will price it at many local pharmacies (including the big chains). It will also give you a link to a "coupon" to get the negotiated GoodRX price at several pharmacies -- which is less than you are likely paying now. I've used their coupons at CVS and WAG, and they do actually take them (it works!). (Don't bother checking Costco--they've consistently been higher than the prices I've found on Goodrx. Walmart is high too, but their pricing shows up on Goodrx).
2. Ask your vet about filling it through Roadrunner compounding pharmacy in Arizona, if they are able to serve your state (your vet has to deal with them -- Roadrunner won't deal with you directly). They are a big national compounding pharmacy that ships all over the country. A single month of Doxy has been running about $70 from them, from what I've been hearing locally. I also heard they recently had a "special" of 500 of the 100mg tabs for 0.30 each, which might work for you, given that you need to have your dog on this for months. If you need to buy several months worth for the tick treatment, maybe that's an option. Your vet has to call them to ask about that special though, and availability will depend on your state's pharmacy rules.
3. Try calling many
compounding pharmacies around your state. One of them told me that the cost of compounding is primarily the labor, so ordering a lot at once is cheaper per pill than ordering in small batches. If your vet will script it that way, you'll save money, since you need several months of this. I saw a huge, huge price variation among the local compounding pharmacies when I called them, so call some in other towns in your state too--they likely can ship it to you, if the price difference is big enough. The key is to ask your vet ask them to compound it in a form to make it easy to dose (e.g., in a 300mg tab since you are giving 3x100mg tabs once a day). They may even be able to flavor it for your dog in a wafer. Be sure you price apples-to-apples (e.g., ask them all about compounding the same form/dose) to get accurate price comparison data.
One of these options should help you get it for less than the retail pharmacy price you are currently paying. It's a hard, hard situation for those of us with pets who need high doses for an extended period of time though. Your vet will likely thank you for helping him or her find other cheaper options for clients!
Good luck! If you find other sources eventually, come back and share them!