griz,
Yes, they are the same drug....but what a silly sounding name seloken zok is.
You should be fine taking 1/4 of the Mexican preparation.
How cheap is "very cheap" for, say, 30 of the 97 mg. tabs "down Mexico way?" Your parents don't even need a prescription do they?
From what I can glean, the Seloken Zok comes in 50 mg. too...maybe easier to split.