This may not even need to be said but if you need to pick up a bulb also be sure to either wait and get the brooder lamp two pack at TSC or whatever bulb you get allow it to burn for 45 min to an hour to get the teflon coating burned off before putting it over your chickens.
http://www.homedepot.com/p/HDX-300-Watt-Incandescent-Brooder-Clamp-Light-HD-303PDQ/204684496
http://www.walmart.com/ip/Bayco-10.5-Brooder-Clamp-Light/14003468
http://www.tractorsupply.com/tsc/product/producers-pride-brooder-lamp-with-6-ft-cord?cm_vc=-10005