Below are some of the places MG dog owners have been able to get the prescription medications needed: They are great. Sometimes you can get vouchers and discounts through them too. The tablets should only run you about 20-30 dollars a month.

Neostigmine injections are very expensive.  Pyridostigmine is usually preferred since it has less side effects.

Pay $70 for 150 pills from a human pharmacy

Can get  generic pills at Target. Called around to Walmart and the local pharmacies and found they were the cheapest. About $60 for 90 pills. 
NOTEDiamondback is a compounding pharmacy that can custom make the medicine, whether it’s pills or liquid. We used liquid to fine tune the dosage and it worked as intended. Not sure why the injectable version would be promoted over the others. My cynical mind wonders if it is just a way to make more money ): One thing we discovered was that there are a lot of vets who are not well versed in these diseases and may make recommendations based on the treatment protocols of other diseases that they do have experience in treating. 

Some Canadian pharmacies are found 600 pills 60 mg each of Mestonin for $326. The generic was only about $20 cheaper.

CVS, Target, or Walgreens Pharmacies

Sam’s Club and Costco

Compounding Pharmacies