then go to Canada or Mexico to stock. It is my strong understanding that they are a lot more liberal with the meds and it is a WHOLE lot less expensive.
I can't speak for Mexico, but it will not be any easier to get narcotics in Canada. Even things like Oxycondone (generic Oxycontin) are highly controlled here.
Our drug prices are controlled by the government, as they are in much of the world, but the maximum quantity of a controlled or prescription drug that you are allowed to purchase or have in your possession is a three month supply, and if you are attempting to bring those items into the country, then you may be required to produce a current
prescription, or surrender them to customs. i.e.: if your prescription was written 45 days prior to the date you are presenting it, then you would be expected to have already consumed 45 days worth of the medication.
If there is any doubt on the part of Customs that your prescription is genuine, your boat may be impounded, you may be arrested and you can be held in a detention centre until you provide proof that you are not attempting to smuggle controlled goods into the country. You will not be compensated for whatever expenses you incur during this process.
It may be possible to obtain a prescription in the country, however pharmacies are required to report on their disposition of controlled substances, hence doctors are reluctant to prescribe the goods unless it is medically necessary. As a visitor to the country, you will be required to pay for the prescribing physician's time. I am not sure what that charge would be.
Me - I would not risk it as the consequences may be exhausting and expensive, not to mention that if you do get detained or arrested, and end up on a "denied entry list" that information may be shared freely amongst all INTERPOL customs and police forces. Trying to land in a lot of countries, particularly the US but also Canada or Britain, when your name has been put on one of those lists, for whatever reason, would be pretty well impossible.
For further information regarding which drugs and substances are considered controlled see:
Controlled Drugs and Substances Act