Is there any unit that I could use both in my car and out on my lawnmower?

I think you can still get the Pioneer Airware. It has a home dock for connecting to your AVR indoors, a card doc for hooking into your radio, and an antenna/headphone available that you can plop on your head outdoors.

Works great for me.

Sure. You can use any of the XM2go units. That would include the Inno, Helix, MyFi, Airware or Tao units.

Is there any unit that I could use both in my car and out on my lawnmower?

Inno, $129. http://www.myradiostore.com/xm-radio-receivers/pioneer-inno-refurbished.html

Inno, $129. http://www.myradiostore.com/xm-radio-receivers/pioneer-inno-refurbished.html

The XM Fan store now have the Inno for $49!!! Sick deal... new subs only, though. Expires Monday.