Let me answer your question!
I am from Brazil and we have the best Gi beeing manufactured here, so, if you wanna buy good stuff here is a website that sells sevral good national brands in Brazil.
Now regarding your question...
No, it does not have problem if you show up in yellow, blue, white, red or black GI for practing... Now if you go to a championship you should go with blue or white, the others colors is more for practing and the Black GI normally is for black belts only!
If you need anything else, just ask.