Hi Hazzar, the tuning module I have is one of these:-
http://www.tuningbox.com/en/home.htm
I didn't pay that for it though, I was lucky enough to find one 2nd hand of Ebay, I think I paid around £60 for mine, I'm sure the ones on ebay can be just as effective. I did a comparrison a couple of months ago, I took my module off and had my car remapped, and was bitterly disappointed with how it felt, and it started using more fuel, so I had a refund and put my Tuning module back on,
The best thing to do is make up your own mind, if you flick through this and other forums you'll find many debates about how good these modules are,some of them get quite heated, people who think they know what they are talking about will say plenty, many haven't driven a car with a module fitted, yes there are risks, if your car has a weak injector these modules will find it and cause a problem, but my view is the pro's far out weigh the cons, many module companies offer a 30day money back guarantee so you can see for yourself, I wouldn't drive my Santa fe without one.
Mike