I'll shorten this list to artists I would buy most/all of the albums of (at least if I had the money), 3+CD compilations, or honourable mentions:
Bryan Ferry & Roxy Music
The Moody Blues
ELO
Dire Straits
Sting & The Police
Pink Floyd
The Alan Parsons Project
John Lennon & The Beatles
Don McLean
Tracy Chapman
Phil Collins & Genesis
Lou Reed & The Velvet Underground (a recent discovery)
The Doors (I bought all their studio albums for my Dad actually, as he likes them more than I)
Cat Stevens (I recently spent $32 each on Deluxe versions of Tea For The Tillerman and Teaser And The Firecat!
)
It would be a fair bet that I'll later think of artists that I wish I didn't forget to put here...