I recommend NOT buying a Hantek USB oscilloscope.
I got a DSO-2250 which sounded good for the money. I would have spent more time reading reviews, this review sums it up.
The software for windows is buggy and limited. They seem to have largely rewritten the software between version 6 and version 7 but have just replaced old bugs with different bugs.
The most frustrating bug is that it gets stuck and stops triggering until you close and reopen the software. It's really annoying to have your hands full poking the probes into some equipment and not knowing if you have missed the packet of data you are trying to catch because it wasn't sent or because the scope software didn't work.
The manufacturer claims 8bit sampling and 250 megasamples/second.
Sadly the hardware is noisy and the lowest two bits randomly change. The software has a smoothing option to hide the noise but then you don't get anything like the time resolution you paid for.
If the software was better I could live with that as I mostly look at digital signals.
I still personally favour a PC oscilloscope since I haul a laptop around and might as well make use of it's high resolution screen.
For digital work a 'scope that can capture a one time event to look at at your leisure is far better than an analog scope that needs a repetitive signal to keep refreshing the CRT.