At this point I think OP should have a clear picture about which advice is to be followed if he wants to waste his money. Enough said about that.
Other things to take into account:
a) It's worth to pay more to be sure the device you are buying does rigth what you want it to do.
b) It's worth to make additional searches before buying, to be sure the device you are considering does right what you want it to do. Don't take any advice in this thread as more than just a heading towards perhaps the right direction. Your homework is to know what you need, and to check carefully the device you are considering is able to do it right, before buying. Learning begins before buying, sorry. If you don't do your homework, you'll be spending your money willi-nilly. You could get bitten, and only you would be guilty for it. People speaking here does not necessarily own the devices you are considering.
c) It's worth to open new threads to ask questions if -after some searchs- you are still unsure the device you are considering does right what you want it to do. Asking questions specifically about some device will probably bring some owners to explain to you what they like/don't like on that device.
d) Even when asking about an specific device, make sure to ask questions and get answers about the characteristics you are interested in. Owners of that device could be not using that characteristic and be unaware of any problems on it.
e) It's worth to buy from some seller that abides with consumer protection law and takes returns, just because you don't like what you got after all.
Last, even on the 400 bucks range, you'll probably won't get all you want. Say you hope to get a device with intregrated logic analyzer. There are devices in that range advertising that capability, but at work time, you could find they are not working as you were expecting.You could need to go up to a thousand bucks range to have a chance of getting that right. That's just an example. There will probably some compromise/choice to be made.
To avoid getting your ass bitten, the only way is to search and learn what you need, to do what you want. Quite a few hours of previous work. It will be easier if you do your homework, so you will be able to ask the right questions. Just a generic question as "best device on 300 bucks range" is not the best thing to do.
Take it easy, and good luck