replace power steering lines

[mdfud]

have an 02 x5 3.0 with about 90k. power steering fluid started leaking about a week ago. took it to independent bmw mechanic that i've used in the past and he quoted me about $800 to replace 1 pressure line, 2 return lines and 1 cooler line. took it to the dealer and they quoted me $620 to replace the 'pressure hose.' i know a little about mechanical stuff but need some advice on what to do here. i'm more concerned about doing what needs to be done than saving big bucks although that would be nice. TIA