Chris,
That is the device that I pointed out to you in my first reply. One thing I forgot to mention is that if you are getting a condenser mic it will need power and the Duo-Capture does not provide that.
Looks like you will need to spend a bit more than you thought. Or you could just go for a second hand SM58 mic, of which there are plenty.
Might be worth saving up and going for one of the better Roland devices. I use a QUAD-CAPTURE but that cost me around £180 at the time (Dawsons are now selling it for £189! and that's where I got mine from).
Sorry I can't be any more help. As soon as you decide what you are going to get, come back here and we'll get you going properly