Sirius has launched a promotion offering two of its top selling satellite radio receivers for free, but only for current subscribers.

The Sportster 4 and Starmate 4 - two of Sirius' best selling units - are available to current subscribers for free if you order by September 15th (and activate the new sub by September 30th).

Not a bad deal if you're looking to give someone else your old clunky unit and upgrade. The Sportster 4 if offered on Sirius' store for $149 before rebate, and the Starmate 4 runs for $119 before rebate.

[Sirius]