All I have to go on are advertisements on ebay and manufacturer's spec pages, where available.
You could try a Microdrive, which is a real ATA hard drive in CF format. The Seagate ST1 goes up to 8GB from memory, and each has a 2MB onboard cache RAM. I picked one up for $20 shipped with a USB converter. OK, so it's not solid state and has moving parts, but it'll still be a lot lower in power use and noise than your average 3.5" hard drive. Otherwise I'd suggest a small (ie cheap) used Seagate HD. They're usually pretty quiet. Or a laptop HD on a 3.5" converter.
What are your reasons for wanting CF in there?