Re: Please recommend inexpensive interface & mic
An SM-57 is the mic I would recommend. It is almost cliche' to mention it because it is so widely used, but it is the industry standard for a reason.
As for an interface, you can find them used fairly cheap these days. I saw an M Audio 2 channel at my local goodwill for $20 a few weeks ago.Jus browse CL or flea bay. You should be able to find a descent one for under $50.