We (Alex Martin, Greg Klein, and Tim Wheeler) had already launched a rather expensive
$800 balloon into near-space.
As college students, we decided to see how cheap we could make a launch, with a basic goal set to be about $150. This involved changing almost everything about how we did the first balloon -- while many of the components of the first balloon were purchased just for the balloon, we made our own equipment wherever possible and substituted cheaper products for various components with a mixed degree of success.
While we were able to create a successful tracking device out of an Motoroloa i290 phone for $50, our $20 party balloon did not perform as well as the more expensive weather balloon we used previously, and this launch only reached an altitude of 6,000 feet.
Althought overall a failure, the tracking system is still considered viable (although untested above the crucial GPS barrier of 60,000 feet) and it is extremely likely that we would be able to relaunch with a better balloon for roughly the target cost of $150.
The payload was recovered.
More information can be found at Greg's blog and at Tim's blog.