how much is that burner? not to be too pragmatic but if $1500's not in your budget, then dual layer media certainly isn't either.
recordable dvd media in general is a poor investment, just that DL carries a huge premium on top of that.
and this won't shave anything off the price, but the x800 pro uses so much less power than any 6800 it's not even funny.
Don't really see any way to save any money there; video card would be the most obvious but I wouldn't want to skimp either if I were you, the x800/6800s are both amazing, have an x800 pro myself... was about to suggest a CRT but then reread your post. There are a million variations of "fast, quiet, cheap, small, easy etc etc pick n-1", if you can't spend more money or get a bigger case, it's not impossible, just it'll take a lot of work.