Nettwerk Music Group has begun testing a variable pricing model for digital downloads in partnership with Passalong Networks and Digonex Technologies.

All music that Nettwerk has the rights to sell in unprotected MP3 format will be available for sale on all 44 stores operated by Passalong networks, using a technology from Digonex that dynamically adjusts the price of singles based on their popularity.

As consumer demand for a given track shifts, the per-track price can be adjusted as low as 29-cents or as high as $1.29.

The test will run through the fall.