There are a few places to get Colombian food. Since it's near me, I tend to go down Venice Blvd into Culver City and shop at Camaguey, which sells a lot of Colombian packaged products alongside lots of other central and south american stuff.
You can also go to the big supermarket, Liborio, which sells stuff from lots of latin american countries, including Colombia. I go to the location on Alvarado/Pico near downtown, but they have other locations. This is a much bigger store than Camaguey.
In the Valley, I know there are at least a couple stores that sell Colombian foods, but they are as big as the two I've mentioned and the prices were pretty high. The same goes for a store that is in Pico Rivera, on Washington, just past the 605 -- high prices, small selection.