In Phil's DVD, he just puts tees in the ground in a circular pattern around the cup, using the putter to measure distance from the cup (about 3 feet for most conventional putters). Pretty cost-effective.
Take a look at the second video in post 74 by mvmac where he discusses this, here: http://thesandtrap.com/t/61376/5sk-video-thread/72
It might not be what's causing your problem, but it's a place to start.
Golfshot used to be good, but the current upgrade in the android version keeps malfunctioning. I get to the course, start up the app, and it doesn't want to work. I have to log off, erase all data, then redownload all...