I've used BD Rebuilder a few times (free software) to shrink double layer Blu-rays onto single layer BD-R. Unfortunately, it takes a LONG TIME. I used the two-pass (normal quality) method on Live Free or Die Hard and it took 10 hours using a Q8200 2.33 GHz Core 2 Quad processor. A few weeks ago I upgraded to a Q9650 3.00 GHz Core 2 Quad, and it cut it down to 7 hours. If you use the 1-pass method it'll about halve the time but quality won't be as good. Some people say it's good enough; kind of a judgment call.
I've used Verbatim for BD-R SL from rima.com and haven't run into any problems. Roughly $3.50 apiece shipped. I've also used TDK and Sony for BD-R DL and haven't run into any problems, but you'll be lucky to find them under $8.50 shipped from e-bay. Which one you'll need depends on your backup method.
1) If you want to do a 1:1 backup of the original, you'll need a BD-R DL about 80% of the time.
2) If you want to shrink the original, BD-R SL.
3) If you strip out all the extras (using BD rebuilder) and stick with main movie only, plus downgrade the lossless audio track to a lossy one, you can usually (90% of the time) get it to fit onto a BD-R SL. Worst case, you'd have to split the main movie to a BD-R SL and a DVD+R DL.
Are you going to use the computer to watch Blu-rays or are you going to use a PS3 or standalone to watch it on the TV? If computer, a 256 MB card while AnyDVD HD is running is probably sufficient. If you're watching it on the TV, it doesn't matter how good/bad your video card is and it's only really CPU power that you have to worry about.