To fit yourself you need two hands, a brain, a drill with a large drill bit, and about half an our tops. Super Electric, if you want to stop round and I'll show you
how to do yours then you're welcome. Where to buy? Various places, but I'd recommend somewhere in the UK then if there's any warranty issues you can send 'em back for much less than it costs to ship recorded delivery to China if they are faulty. No doubt the Chinese ones are loads cheaper though, but for extra peace of mind consider UK suppliers.