I've put 18,000kms once on a tire that was first patched with a sticky string and then patched from the inside.
Mexican tire repair shops know how and when they can apply a vulcanized interior patch. I've never been to a tire shop here where the guy doing the repairs has made a decision I wouldn't trust. If they tell you it can be done, they will do it and they won't charge you very much.
The repaired tire I had, I used down to the cords here on Mexican roads.
If you are looking for a new tire, prices will vary considerably depending on where you shop. Usually, dealers will charge you a small fortune, especially the Japanese bike dealers, however, there are usually at least a few good accessory shops that have common sized tires in stock and will direct you to a good place for mounting, but balancing can be harder to find. If you want to buy bike parts in Mexico in a city you don't know, ask the pizza delivery guys or the other delivery guys who use their bikes all day, every day. They, or the manager of where they work, will usually recommend a place.
In Mexico, you will often find the MotoMundo locales, but they are always the most expensive, other than the dealer.
MotoMart locations are usually cheaper but you might save a few pesos by shopping around but it isn't worth it sometimes. I've seen some tires here cheaper than in the US.