Dream Theater - Awake @ Play - £2.99
Dream Theater - A Change of Seasons @ Play - £2.99
Dream Theater - Falling into Infinity @ Play - £2.99
Dream Theater - Images and Words @ Play - £2.99
Dream Theater - Live at the Marquee @ Play - £2.99
Dream Theater - Live Scenes From New York (3CD Box Set) @ Play - £3.99
The majority of these are out of stock. The pages say 3 - 5 days and when you go to checkout they appear as out of stock. Cracking price for them though and you'll eventually get them.
The rest of these are from various other places but some of them are still bargains as they are often a lot more expensive.
Dream Theater - Score (3CD) @ The Hut - £5.00
Dream Theater - Once in a Livetime @ The Hut - £5.00
The albums I've missed out are the ones that you can usually get cheap (~£5) most of the time.
See the first post for links.