with Betson, they'll have everything you need pretty much. I've seen a lot of those pads and inverters and stuff on ebay too for I believe a lot less than what they'd cost at Betson. I know for sure that the CD-ROM replacements they sell are grossly overpriced, and I happened to replace mine with some random Sony unit that I got in a comp my cousin gave me... I know that's not what you're looking for, but there was another thread on here compiling all the compatible drives that work with DDR. lol
good luck.