Clothing?? (San José)

I plan on travelling to costa rica in December Protected content , i plan on biking across the country to my new home in cahuita, i will only be flying in with my mountain bike outfitted for the trek and whatever i can carry on my back, i dont need alot to survive, my question is can i pick up some decent priced duds in CR, or do i have to pack an entire suitcase, (i would like to only have a change of clothes and pick up a set or two for a reasonable price in san jose (in the usa we have a place called ross! where you can get good clothes cheap)

Curious as to thoughts on this!