I have used these guys in the past for Suzuki parts. They are a big Suzuki dealer located in Monterrey. If they have the parts in stock they can send them within a day and have them to you in 3. If they have to get the parts from somewhere else it will take about a week. I'd call them for you to see if they have the parts in stock but today is Sunday.
They can send the parts anywhere, a hotel etc. You are welcome to send them to me in DGO if you can make it here with the sprockets you have. I have some experience in running very warn out sprockets
and my guess it that you probably could make it here depending on how much time you plan to spend in Copper Canyon.
The way mail order works in Mexico is that: 1) You order the part fom the vendor, 2) They give you a bank account number, 3) You go to the bank and deposit the money in the account and the bank gives you a confirmation number, 4) You give the confirmation number to the vendor and they check that the deposit has been made, 5) They send the parts. It is kind of a pain but the whole thing can be done in less than an hour.
If they have the parts in stock this is the best bet, in terms of time. If they dont, any motorcycle shop in Mexico can get almost anything within reason for you in about a week. If you order from a shop they save you the trouble of having to go through this process. There is a good shop here in DGO that can get the parts in a week.