Check out the new pingBuddy2 dual band ADS-B receiver from UAVIONIX:

http://www.uavionix.com/products/pingbuddy2/

$149. Works with a wide variety of iPhone and iPAD aps, including Foreflight, FltPlan Go, WingX, etc.

Provides weather, and traffic (both ADS-B equipped A/C, and Mode C/S transponder traffic via TIS-B). Note: To reliably see traffic you need to be ADS-B OUT equipped.

If you already have a TRIG transponder, add the new TN72 GPS position source for ~$500, the pingBuddy2 for $149, and the free FltPlan Go app on your iPhone, and you have a complete collision avoidance system that will show you every transponder equipped aircraft in your vicinity with voice alerts for anyone getting too close.

If you don't have a transponder yet, this will give you a great excuse to buy one.