USB scope: $35
RPi: $35
Battery: $15
Screen: $35
hm.
RPi: $35
Battery: $15
Screen: $35
hm.
My big problem with a USB oscilloscope is that they are only ground referenced through the USB ground to your computer and if you measure something with a different ground reference you can blow up the USB port on your computer.
Gauging from the job postings on their website, I have a hunch/dream that the folks at Saleae are cooking a decent USB scope up as their next product offering. Would love it if they did. Saleae's Logic Pro 16 is without a doubt the best designed EE tool I've ever used.