Jerseys and shorts are not the same as t-shirts and jogging shorts. They are made of modern materials designed to wisk moisture away from your skin, keeping you cooler in warm weather.
I too suffer from sticker shock. At the beginning and end of the cycling season, bike shops have clearance sales. I have found excellent prices there. I have also found great prices on quality gear at longcycle.com. There are a few other sources as well.
No I am not advocating abandoning your local bike shop. I use online sources for items that I could not justify buying locally for more (besides, my wife would divorce me and not only did I pay more than I could afford, I also have to pay alimony and child support ); )