I am sorry, I have'nt seen anything. Most of the Mariachi costumes out there seem to be beyond your buget.
I would suggest go through your closet and see what you have, first.
What youy don't have, go to Goodwill or a vintage store and purchase any needed items like, pants, jacket, shirt, etc.....you could even do a vest, if you can't find a black jacket. Then go to JoAnn's and buy white appliques, silver brick-brack or metal buttons , some red material for a belt or a scarf.....to try to achieve your Mariachi.
The hat should be able to purchase or rent at a costume place.....
Here are some examples to give you some ideas. Good Luck!
H1
A DIY Mariachi Costume- This webpage has quite a few pics to get some ideas.
Oktoberfest2 2007