Sorry that folks have not been more helpful.
How about a 5 channel version of a gainclone? Easy to get your power, and plenty of information about them out on the Net.
I would also consider buying a used 5 channel amp - lots of those around on Audiogon etc.
As for speakers, I if you are using a good sub, I would look at 4.5-6 inch full range drivers in sealed boxes.
I have had plenty of success with the FR125S (either DIYCable or CSS in Canada).
If you are not looking for DIY speakers, I have helped friends build up cheaper 5, 6 and 7.1 systems using available used bookshelf speakers. There are usually lots of brand name pairs around eBay - Mirage, Paradigm, Boston etc
Have fun!