Firstly, i apologise for the prices in £'s; when you live in the UK, there isn't much call for working in $'s. in terms of audio interfaces in your price bracket, there are a lot available with all subjective pro's and con's. assuming that you'd just need one or two inputs, and that you're happy with USB, then the handful that spring to mind are;
the Focusrite Scarlett 8i6 - £150, great sounding pre's, and an expandable to 8 in's if you wanted more inputs in the future
Presonus Audiobox 22VSL - £160, nice sounding pre's, and some built in DSP effects that can be useful when recording
Tascam US-600 - £160, good sounding pre's, and four mic inputs
Maudio Fast Track MkII - about £90 (depending where you look), only one mic in and one instrument in, but very usable
Alesis io2 - £80, 2 ok sounding mic pre's, some driver issues that are seem to be fixed easily with some free software (
ASIO4all) but for a starting point for 2 in's it's not bad
in terms of mic's for your style of singing, again there's plenty out there and it's all very very subjective, but i'd suggest looking at/
listening to/trying;
Rode NT1a and/or NT2a
sE X1 and 2200a
AKG C214
Apex 460
I'd also recommend sorting out at least some simple treatment in your space. even if you just sling a duvet behind yourself and some sort of reflection filter behind the mic when singing it should make quite a noticeable difference, and with that in mind the
sE X1 bundle is a very good package for £190.
With the interfaces i'd say pick that one that suits your needs best as the quality difference in this price range is so small and more often than not the choice comes down to what the interface offers in terms of number of inputs, outputs, and extra gubbins (i.e the focusrite stuff comes with some free plugins, the presonus stuff has some simple DSP for proving reverb and effects in your headphones whilst recordings, the tascam has 4 mic inputs, the alesis is cheap etc)
with mic's, the best thing to do is try as many as you can and see what works for you and what doesn't. if you can't try them, find audio clips and listen to them, but take these kind of samples with a pinch of salt and always remember that's what that mic sounds like on that source in that space.
and a duvet and reflection filter style device are very VERY worthwhile investments