I'm pretty sure you're not going to find a turbo or supercharger kit for ML320 for anything close to $5K Cdn, or even $5K US. A turbo- or super-charger conversion will require some internal engine modifications to be reliable and durable. E.g., lowering the compression ratio so that you can actually use the extra charge.

You may as well just go down to your dealer and put down a deposit for the 2002 ML500. I'm not kidding.