Any question answered...

I have to record an interview but I'm also super skint. The audio quality doesn't have to be amazing but definitely better than an inbuilt mic on a dslr.

Any suggestions, something Chinese and from ebay perhaps or something decent and secondhand? Not got a clue where to start with brands/types at all

Well all the dslr video crowd swear by rode video mics. They are fancy and sort of industry standard. But affordable and a useful piece of kit to have;

http://www.juno.co.uk/products/rode-videomic-go-on-camera-microphone/514252-01/?currency=GBP&flt=1&gclid=CJbul5Lvvb0CFQKWtAod1WgAsw