I'm thinking of getting a parktronic for my ML320.

Any suggestions on an alternative.
Does anyone know the price of the OEM for the ML320?
Is it hard to do a DIY?
Alternatives?

I don't think Parktronic is a DIY project but I know there are less expensive aftermarket products you can buy and DIY. I have Parktronics on mine because I like the audio/visual display and it's well integrated with the vehicle.

I had this one installed last week. Very, Very happy just for $26.00 . Very easy to install.
Check this out.
http://www.overstock.com/cgi-bin/d2.cgi?PAGE=PROFRAME&PROD_ID=21092

there is a small round bar under your bumper,actually that holds the spare tire. go to any hardware, look for a 1/4" eye catcher(that`s what it called).

can you describe the pros and cons about the back up sensor you got? the amount of beeps tells you how far away you are from an object?

After everything is fully installed, you put in reverse you will hear a beep- to let you know the SmartPark is in operational(that`s the first zone of detection(safety zone).As you start backing up you will hear a continuos beep- second zone of detection.Then when beeping increases in frequency and changes in pitch you are now in the third zone of detection- you should stop. This is only the basic principle. You may adjust the distance of the zone depending on your preference . the beep is so cute too.

back into a tree, person, or pole does it beep? or only works during parellel parking?

Actually, I put three objects at a time - my wife, blue garbage can and the frozen ice.On the last zone,when it starts to beep intensely there`s a margin for at least 2 feet. By this time, you can either stop or back up a little more, it depends on your judgment.

Shows how much you love your wife ^_^ 2 ft? so how can you parellel park? 2 ft that is too far!