I must warn you.. it's not for the faint of heart. One glass usually does it! ;-)
Add Margarita salt to the glass if you wish, but don't ommit in the recipe. Gives it a little something extra.
If you can't find sweetened lime juice, ordinary lime juice is fine. Just add sugar to your liking. Or substitute with a mix. Master of Mixes Margarita is the best.