Why won't the brake lights cut off?

You will have to check the brake light switch it self, it is located at the top of the brake pedal, it will proberbly be out of adjustment or faulty.

I can't find a pic of your exact type, but this is a average brake light switch, it will be located at the very top of the pedal or at the top of the pedal box, the brake pedal will operate it.

With the pedal up, there should be no power through the switch, probe both sides of the switch with a test light, you can unplug the switch and if the lights go off the switch will be faulty if you only have power on one site of the plug.

Dealers will be more expensive than after market, normally it will be a buy in so you may have to wait a day to get one, after market I would expect to pay around $40-50 at full retail. You can get cheaper but often these are not the best quality.

You can try adjusting, there should be a lock nut that you back off unplug the switch and turn to adjust, worth a try.

Try a web site call parts train they have a big range, as for the parts of on model to another some will some won't often if the part # is the same it will be ok, just be careful with any electricals that's all.