Okay this info may be of use for others.
I recently bought a Nintendo wii off ebay. I did a bit of research. I you search for 'refurbished wii' you will notice that 1 company is offereing them. This company is Argos with a 7 day money back offer.
I was lucky as mine is moddable, however I paid pretty much the same as you can buy a new one.
So realistically for the risk of return postage it is possible to get a 12 month warranty on a moddable console. Sadly I trust once it is modded the warranty is out of the window.