depends on A LOT of things. Where you live (how bad the roads are, does it snow) how low do you want to drop, would you really need the ability to raise and lower your car at certain times or ocassions... and of course most important of all... your budget.

P.S. i hope your "very good deal" is not an ebay deal.
Theres certain things that are alright to buy off ebay, and certain things its best to search for genuine brand names. "You get what you pay for" is something everyone here will tell ya, and it's VERY true.