What's the easiest way to power a stereo outdoors for 2 hours a day? Battery,

generator etc? Basically I want to power a decent sound-system in a gym I have at the end of my garden for around 2 hours per day (the room has no power). Running an extension cord from the house isn't really an option because it would have to cross the driveway. I ideally want to just be able to go down there when I fancy and have power straight away. Few other potential ideas I've had:

1. Leisure battery (expensive? Would it last 2 hours a day?)

2. Standard car battery with an inverter - to convert the battery to a 3 pin plug. (Would this last for 2 hours? Would I ruin the battery by constantly running it down then recharging?)

3. Generator (not ideal due to noise etc but may be only option?)

Looking for a low cost, but effective method.. ideally totalling no more than £50. Which one of the above looks the most realistic/convenient? If anyone has any better ideas I would really appreciate hearing them.

Thanks a lot!

A stereo doesn't draw much.
A rechargable battery/inverter inverter unit would probably be cheapest
if you plan to do a lot of it, long term.
'Trouble is' batteries are expensive.
A good battery, properly sized, will last a very long time and not suffer damage
if left on a 'smart' battery charger/tender unit when not in use.

This has got to be cheaper

http://www.electriduct.com/cable-protectors.html