Which Is The Best Kind Of Chair To Get To Use A Desk When I Am Working?

As I sit here with a cringing back ache, I am wondering the very same question, what chair could I buy that make my back feel much more pleasant and relieve me of this pain, and yet be comfortable enough for me, without being a big expensive chair.

You should look for two things, comfort and its ability to be adjustable.  Adjustable height is important, it allows you to sit at a desk at the right height and allows for your arms and wrists to be relieved when typing.  The back rest should also be adjustable, changing the position of where the support on your back is received. Sometimes arm rests give support, but tend to be almost unnecessary:

However, there are thousands of chairs on the market.

There are two that I would thoroughly recommend and am thinking about purchasing and I've tried both chairs in the past:

The first is the ugly but immensely comfortable, a freak god of engineering, the Aeron. These retails at very high prices for a good one.  The other is an ergonomic kneeler, which has no back to it, but allows your natural posture to be pushed upright by kneeling at the desk.  This is my favourite and probably the one I will get until I can afford an Aeron chair.