The guy at the bike shop said I could find the bulbs at the autoparts store for cheap. But does anyone know the size? Also, is there a walkthrough on dis/assembling the gauge cluster on this site? I'm a newb to bike mechanics.

This thread should provide all the information you need. Searching the forum/wiki is usually a good first step.

Straight from google:
Instrument Cluster and Headlight Bulb Replacement Part 1
and Part 2

Thanks. I did a couple forums searches and found nothing. I probably didn't use the correct search terms.

I've used the #194 bulb available at auto parts stores and Walmarts for speedo, tach, and all four indicators on both my 97 and 02 GSs.  Not sure if they're all the same for 04 and later F models.

I went and got the 194's from Mallwart and used those.