There is a place that sells the Dynatron CF-001 which appears to use the QG030 fan (probably the 51cfm version).
If you remove the motor cage, this fan will juuuuust fit in that little area above the expansion ports in a typical ATX case.
The Dynatron sells for $17, but they're hard to find, and Dynatron is in Germany (I think).
If you guys are talking about a different kind of fan, pardon me.