Well the whole point of peasants is that they should be wearing shitty, boring and cheap clothing that isn't designed by elven Armani and D&G.
Cheap does not mean brown. Cloths were more durable and more cared for in middle ages, because there were no factories, so cloths were more expansive. So when you bought cloths, you made sure it's nice and solid, because you will be wearing it for next 10 years, repair it a few times, etc.
Buying cloths then were more like buying a car today.
Look at this. http://www.gnosis.art.pl/iluminatornia/omnibus/bracia_Limbourg_czerwiec.htm
Or this: http://www.stankiewicz.e.pl/index.php?kat=10&sub=64 (Chłopi means peasants, Włościanie means rich peasants, Żydzi means Judes).