New 2007 BMW X5 pricing issues

[ghaitma]

Can somebody help me understand this pricing nightmare? I am on the market for a new 07 X5. Checked BMWUSA.COM for pricing. I came with $51,825.00 for a brand new 07 X5 with these options: Technology package, Premium sound package and BMW assist. But a dealer in the Miami area is asking $53,771.00 for a used 07 with 1,500 miles without any option package and another is asking $53,995.00 for one with two option packages: premium package and technology package. what I am missing here? what kind of hidden prices are in there? Please somebody help me understand because I don't want to make such an expensive mistake.
thanks.