Have a look at this site:

http://volvospeed.com/bay13.htm

It has instructions for many repairs including timing belt. Many
people have done it themselves following the site instructions.
Most people say take your time; don't move any engine parts once
the belt is off; work in an area with lots and lots of light (note
that the hood can be opened 90 degrees vertical [to help with light]
by rotating the stops on the hinge back and up).

The downside is it is an interference engine and if you mess up you
will damage pistons and valves. I recall one person here reporting
that happened to them.

Since a 93 has a more frequent replacement then other years, I'd
learn to do it myself.

A new belt should be about $40 from a volvo dealer. I'd only use
OEM parts.

Finally, double-check the instructions for any reference to 93; 93's have
a different belt and replacement schedule and the number of people to draw
on here who have done 93s is probably low.

I'll also throw in a pitch for IPDs (ipdusa.com) tool for removing
the accessory belt. Makes the job easy and they include updated
routing instructions for newer belts (this is the accessory belt, aka
the fan belt).