Shutter count is the number of shutter actuations that occur each time the shutter opens and closes when taking pictures, whether in raw or jpeg format. Earlier SLR cameras were designed using older technologies, so their shutter lifespan may be shorter than the newer DSLRs. When you are considering to buy a new or used DSLR, it is helpful to do some research on the camera model you are interested in, by reading some reviews on the internet. There are no lack of camera review sites online, some offerings are more brief and others are lengthy. Some of these reviews also disclose the expected lifespan of the shutter lifespan. For example, in the review of the Nikon D90 by Ken Rockwell, the shutter lifespan is estimated at 100,000.
Personally I would consider a low shutter count to be at 10%-20% of the lifespan.
Hope this helps.