I bought a Brother about a year ago when my trusty Toyota finally hung up its boots. I'm really pleased with it, a very sturdy machine, with a range of stitches. It would be outside your price range, but Brother have machines for around your budget.
I have to say my absolute favourite feature is the automatic needle threader, as I have spent so so long in the past trying, and failing, to thread the needle. Now it's a doddle. If you have trouble with your eyesight, you might want to look for a machine that has this feature. Unfortunately the Brother machines with this start at over £200 , but there could be other makes that are cheaper.
If you want a basic machine, that just does straight stitch, zigzag, sews on buttons and does buttonholes, then there are plenty available for under £100. Argos have this one for £79.99. But it's currently even cheaper at Hobbycraft, at just £64! And they have several others under £100