Zack had his first United Nations parade a few days ago. South American countries were assigned to his class and we chose for him to represent Brazil that day. Actually, I wanted him to don an Ecuadorian traditional costume but I wasn't able to find a poncho-type costume when I was in Quiapo. So I opted for a traditional festive type Brazilian costume for Zack instead. I think it went really well!
If you are looking for traditional costumes for United Nations or Linggo ng Wika, Quiapo is definitely the place to visit! There are two known locations that sells costumes. The first location is at Evangelista St. From Paterno St. (the street before Quiapo Church), just take a left to Evangelista St. From there up to Quiapo Church, you'll see the stalls that sells costumes. There are probably at least 10 stalls that sells various costumes. The second location is at Palanca St. This one's near Excellente Ham and SM Quiapo. From Quezon Bridge, the stalls are located in the right side of the street (almost at the corner of Palanca and Villalobos Sts.). There are lesser stalls at Palanca though. When looking for costumes, just tell them the country that you need and they'll give you suggestions because obviously they don't have costumes on hand for each and every country. They usually have more options for girls though so it won't be a problem to look for costumes for girls. They likewise sells costumes for adults, head dresses, and other accesories. Prices start from P300.
I got the costume from a stall at Palanca. Everything, including the hat, costed me around P500. But I think if you haggle better, you could get better prices. There are also flags available there but I opted to DIY his Brazil flag. Anyway, I cannot remember similar events like this when I was in school. But it's definitely fun to make Zack wear adorable costumes because I think he's in his cutest stage. :p Hope this post entertains and helps you!