There are many cheap axes, mauls and machetes available but they ofter don't cut as well as they should. It doesn't seem to be the steel, although obviously you won't get Gransfors quality for B&Q prices, but more the hand finishing of the cutting edges. Or more specifically the lack of it.
I have experimented with improving the shape of these bargain axes with bench grinders, files, angle grinders etc etc.
Now I have found the ideal tool. A "Flap Disk" is a disk that fits to a standard angle grinder and has many flaps of emery cloth attached:
http://www.instructables.com/files/deriv/FRF/IOMM/F9AZJK09/FRFIOMMF9AZJK09.MEDIUM.jpg
These work really well, gentle enough to allow a good shape, they leave a really smooth finish without gouges, and they are sharp enough not to overheat the steel near the edge - although for a cutting axe you should always leave the very edge to be done with a stone for best finish.
Finishing your axe or maul to the correct profile with one of these makes a real difference to a cheap tool.