Most trailer supply places will carry the harness kits for less than $50. Figure about $10-$20 for the self-resetting circuit breaker (available at trailer supply places). The brake controller will run $50-$75. Most trailer supply houses have kits available that plug directly into the factory connectors and are much more reliable than generic splices and are almost idiot proof. These will connect tail lights/brake lights to a generic flat style 4-pin connector. Then add a 6-pin or 7-pin connector adapter (to match your trailer connector) and wire the extra wires to your brake controller and to ground respectively.

The advantage of the 4-pin connector is that if you ever use your tow vehicle for towing something else that uses a standard flat style 4-pin connector, you just unplug from your 4-pin to 7-pin adapter and you're all set.

Use lots of electrical grease on all connectors.