if it is indeed indexed, sometimes i can get away with just replacing the crown race. these can be purchased for a few dollars. they come with two common inside diameters. make sure you get the right one if you go this way. the LBS may be able to install one if you've already got the correct one. but then again i think you can purchase an inexpensive tange m30 or something for about 15 dollars, online.

or, alternatively, it's always possible to just take it to the LBS and say "i think i need a new headset, how much do you charge to install the most inexpensive one?" or words to that effect. last time i did this i think it was about 45 dollars all together.