Should sell fast at that price and low miles. Looks mint. 2002 Cadillac Eldorado ETC 2dr Coupe - cars & trucks - by dealer -... (craigslist.org)
Has everything going for it except the Northstar. Would suggest any buyer assume they are paying $10,000 for this Caddie, $5,000 for the car and $5,000 for engine repairs.
$5500 for the car is still too much if the head bolt fixes haven't been done. 55k miles is just at the beginning when those problems start to surface. Everything on these cars is expensive to fix due to GM's high end unique features on Cadillac such as suspension, the electronics and just plain age.
I have a 2001 ETC I have had since new. It did not blow the head gaskets until 130k miles, although it had other problems before, such as when the sunroof failed in the open position. That was a pricey repair. When everything is good, these cars are a joy to drive. But the upkeep is quite expensive - that is true. I've sunk more into mine than I would ever get out of it, so I keep it around as a weekend driver at this point.