99 taurus door switch

The door switch on the drivers side is not working.  I haven't asked the dealer, but my non-dealer mechanic thought the switch may be in the lock and is probably expensive.  I was thinking of installing a good old fashoned pin switch in it's place.  The guide shows the trigger as a positive, so a good old fashoned ground wouldn't work?  I tried to find the switch in an aftermarket repair guide, but it didn't have door switches listed.

I really don't care so much if the "car" knows the door is open, I'm only concerned with the alarm, so I could us a pin switch directly to the alarm input.  Use the existing door trigger (for the other 3 doors) as an aux input?

Or should I poney up the bucks for a new factory switch?

Thanks