How long is a piece of string? If you want to record on a PC, as a minimum you need:-

1) A mic interface - I use a Focusrite Scarlett 2i2, but there are loads of similar devices out there.

2) One or two decent mics - a large diaphragm condensor is good for vocals, a small diaphragm condensor for guitar, but if your requirements are very basic, you could just about get away with one.

3) Software - Audacity is freeware and pretty decent, I use Reaper which gives a 60 day free trial and is not particularly expensive to buy. There are many others - Cubase, ProTools, and others. How much you need to spend depends on exactly what you want from the software.

4) A decent-spec PC.