Can you pop the speakers from the dash? To do so, take any battery (a typical AA will do) and with the speaker connected, touch one of the two speaker wires to the + of the battery and the other speaker wire to the - of the battery. You can use additional wire to jump to the harness or whatever it takes to connect the wiring to the battery. Incidently, this is a good way of establishing polarity of the speaker: if you do this and the speaker goes out, then whatever wire you have touching the + side of the battery is the wire that's leading to the positive terminal of the speaker.
So, I'd check that to begin with. If you can pop the speakers from the dash then you have a connection running from the dash to the speakers. If you cant, then the connection is broken somewhere or feeding into a factory amp that you may not know about. That's something else to consider: if whoever it was that did this was willing to change out the harness in the car, what's to say that the person didn't do something silly like try to add a bose amp or something. I seriously doubt that's the case but it's something to consider.
Normally under many circumstances, the speaker wires from the dash will usually go into a factory plug in each kick panel. The plug will connect the wiring from the radio (traveling through the dash to the kick) to the wiring in the door (traveling from the kick to the speaker in the door, through the door jamb). So, if nothing is changed from the dash to the kick, then the wiring at this plug will have the same colors as what's in the dash. You can also double check this by using a digital multimeter and checking the continuity between that plug and the dash. If you read something close to 0.0 ohms (0.5 something in that range), then you are doing great. Naturally, the wiring is a different color at the kick, then something has changed in the dash. Keep in mind that regardless if there's a plug or not, there is some method of the wiring going from the kick to the door. I have yet to see this happen without a plug of some sorts.
Even if you can or cant pop the speakers or whatever, it is so remarkably simple to run wires in the car... it just takes a little time and patience. I'd run minimum 16 gauge wire, and run through the door jamb (there's info in this site about doing this--it's not hard). Run the wire from inside the door, probably leaving around a good 12 to 16 inches in the door to work with... go from there, through the jamb, under the dash to the back of the radio. Sometimes the area that houses the radio is encased in plastic making it difficult to run wires to that point... a Dremel works well on this (hey! it's just plastic!)--just make sure you dont cut through a wire or something (it's highly likely you wont). Do this for both doors and you are done. It's probably an hour job or so, maybe an hour and a half and it will cost you all of $10 for wire, if that much! So, you go into it saving a good $40 to $60. I wouldnt throw the money away on getting someone else to do a job that you can do!
It's so worth considering. At any rate, start with popping the speakers. Look for the plug in the kick. Test continuity from the dash to kick--if you have continuity, go from the kick to the door; if you dont, trace or rewire from the kick to the dash. If all this reveals nothing, run new wires. Again, it's easy, it's simple, and something you can do for considerably cheaper.