If you already have a PC a

If you already have a PC and don’t want to get a new computer for this, you could consider something like Premire Elements.

Of course you could always be brave and use Windows movie maker, but I think that only has 1 audio track (I’m not positive about this). It’s pretty basic, but combine that with Audacity (free software) and you could have a system that can mix audio and cut video together for pretty cheap. It’s not the best solution, but it’s the cheapest (assuming you already have a PC) and it should be able to do everything you want to do.