Well, less than eBay is hard to find, especially if you want them to work properly
I bought my whole computer off eBay, but I don't advise people doing this, because, 1) the components might not work, 2) if 1 applies, once you pay the seller can ignore you (for example, not reply to your emails). Even if you give them negative feedback, they still benefit.
Luckily, all my parts turned out OK

But the problem I had was that I could only test them out on the 25th (xmas day). And I was buying them in October & November. This meant that they could have gone a left eBay in that time ,lol, or anything like that. But anyway, here I am blabbing on... (if you want to see the specs of my computer, look in my signature, amazing for £180).
The only place I could suggest that might be a tad cheaper is a Computer Fair, there a lots of these everywhere in your local area. You just have to look in the yellow pages or something similar to that. You'll be surprised how many you might find.....
Good luck mate, and happy videoing, lol!