I have had two of the $5 Chinese usb-midi things and they work just fine. The only issue with them is that they are made so insanely cheaply that if you are going to be moving it around a lot you may want to get something more rugged. But, if you're going to connect it in, say, a rack situation or tuck it behind a desk (or whatever) and leave it for good then you can't complain over $5.
With that in mind, personally, I recommend anyone who has even the slightest inclination to ever get a floor board/controller to get a usb-midi device that has channel merging - whatever that's technically called. The only way to have the Axe-FX plugged into and working with both the Axe-Edit software and a foot controller type unit is to have a single midi device that sums the input channels (eg. Midisport 2x2, from what I've read).
So, either buy the cheap, $5 thing now and get the combiner thing-a-majig later, or just buy the combiner thing-a-majig right from the get go. Otherwise you're going to be wasting money somewhere along the line.