Dicks's has sportsman's cushions on sale for $6.99 (Heat a Seat for Hunters); a great price. Buy a cheap clip so that you can attach it to your belt loop and walk around in the woods with it attached to you, or to your backpack.
Make it your permanent meditation cushion. Meditate on it at home, in the woods or when you travel. It will retain your imprints of meditation, thereby making your meditation deeper and stronger.
If you are serious about meditation buy yourself a meditation cushion upon which you meditate on all the time.