Outside of going to the dealer and paying as much as the car is worth for a new DIM, Xemodex is probably the way to go. It will still cost you at least $350 but you'll get a properly functioning DIM with minimal work on your part. In fact they advertise that they actually install some upgraded components like additional heat sink, etc. to improve future reliability.

The next less expensive option is to call Erie Volvo and see if they have a used one that will match up to your car. You will have to remove the old DIM before calling them so that you can give them the code numbers off of the back side of the DIM. This will probably run you about $150 these days.

The absolute cheapest option is to visit the pick-n-pull wrecking yards and start pulling out 2002 Volvo DIMs until you find a code number match. Then hope it works when you get it home.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)