Margarita variations for a street party
Hey all,
I'm looking for some tried-and-true variations of margaritas to sell at Queensday, the Netherlands' biggest street party*.
I'm looking to sell margaritas outside my apartment. Limes can be expensive and hard to come by in this neck of the woods, so I'm wondering if anyone has a variation that cuts down on them: lemons, oranges, other citrus.
For any bartenders out there, what's the standard amount of liquid given in a cocktail? I don't want to stiff the Dutchies.
Other cheap-n-easy variations on cocktails are welcome (cheap being important).
*There's no sales tax on that day, so everything turns into a massive yard sale. Sure, selling food or drink is technically not allowed, but everyone does it :)

Making this for Cinco de Mayo. Is there any alternative to using a Dutch oven? I, strangely enough, live in Holland, but have no such apparatus (or an oven big enough to fit one).