In addition to Mitch's suggestions, try Active Endeavors (it is walking distance from the campus, on Chicago Avenue). They have a nice selection of clothing and camping, and a reasonable selection of kayaking gear (on the second floor).

While located further away, the best selection of kayaks & gear I know of is Chicagoland Canoe Base---a very neat store!

Websites are:

http://www.chicagolandcanoebase.com/

http://www.activeendeavors.com/stores/