I agree,
I was super close to buying one online but had a chance to play one in a shop and decided that while it kicked most commercial things ass it still didn't quite cut the mustard.
yeah, but Im no good at building stuff and electronics.
I mean, I can afford the xarcade, so seems easier to avoid the hassle of trying to building it and failing.
Experience really isn't such a necessary factor in this hobby. Dont be scared of building a PC it really isn't much harder than plugging in your VCR, all the plugs only fit where they're supposed to go. Any computer store will help you to make sure your parts are compatible with each other.
Not sure where you are but I'm in Sydney, Australia and there are heaps of little individually owned computer stores run by sweet little asian guys and ladies that offer great prices on all the bits you need and will often put it together for you for free,
As for the arcade controlls I'm still waiting for my keyboard encoder so can't be certain but it doesn't look like brain surgery and there are about a hundred step by step guides floating around these parts.
I can however understand wanting to buy a pre made box to house your controls to get a professional looking finished product. My woodworking endevours never look very beautiful.
It will probably cost you about the same as an X-arcade in the long run but well worth the time, plus you end up with exactly the controlls you want.