Cotton is cheap, and unsuitable for this purpose. We're not in the previous century anymore, synthetics are much improved these days, take a look at technical materials such as Coolmax, and similar, try wearing them for a while, and then go back to wet, heavy, stinkin' cotton. I am pretty sure you're going to ask yourself what were you thinking wearing cotton all the time. Cotton simply does not work for this, and when it gets wet it's all over - get caught in colder rain in cotton, you can get hypothermia and cold in under 15 min. It doesn't wick sweat effectively, and it doesn't breathe at all when it's wet, you might as well put a common nylon bag over instead of your clothes, wet cotton feels the same to me - hot, wet, sticky and non breathable. It doesn't dry nowhere quick as a good synthetic does. It is an unsuitable fabric for the application, it might work just barely ok on short, easy summer commutes, but not much anything else. A proper set of clothes, is in my opinion and experience having done more then 5,000 miles on bike in any weather - blizzards, snow, ice, thunderstorms, pouring rain, sun - proper set of clothes is invaluable personal gear, just like gloves, helmet, and lights as a bare minimum. And such clothes can be had for cheap today, if you shop around.