Get yourself one of these. http://www.maplin.co.uk/easy-fit-car-alarm-347077 My dad had his car broken into last week, so I got myself on of these for my mk3 which is not garaged and has no security alarm as standard. It was easy to wire up, does exactly what you could want and is cheap as chips for those who dont have a lot of dollar spare. Thats is all. Mike.
Would you really want to protect your p&j with a 20 alarm? As these units are simple to fit they are simple to bypass. You are better putting your money towards a Disklok if you can't stretch to a proper alarm.
I think your missing the point. Not everyone can afford an expensive alarm and in my case the only reason it was purchased was due to the fact that 'theft of contents' had taken place. It will alert me enough should anyone gain entry and therefore is well worth 20. I am not expecting it to withstand a 'trained car thief'. Just aswell my mk3 diesel runaround isnt my P&JMike.
I was in simlar boat when I had a jap import Toyota, so I bought a second hand clifford off ebay CAT 1 alarm and wired it in myself. I managed to get the circuit diagram off the net and worked a treat. Cost me peanuts compared to what it would of cost new!!