I guess you could just end up using a cheap used 200$ lap-top on battery power. If you want to see the display and control it from your main PC, you can use the WiFi, or, preferably 1GB lan (Ethernet is transformer coupled isolated) with remote viewing & control software like VNC. (1 Gb lan works really smooth with VNC even in 1080p)
The battery power laptop will give you that isolation from the wall AC on that side. I know this might not be perfect for you, but, if you are going to spend 200$ on an isolator, this might be a workable alternative...
It's too bad there isn't a 1GB lan version of the USB scope.
BG.