Romeo Romeo,
Your question is a good one and you can get some answers
here. As you can see, £100 is a bit low, if you want decent GA traffic avoidance systems you will be using TIS and paying $5k + whatever it costs to fit.
Unfortunately TIS needs ground equipment/software and I doubt you will see this in the UK any time soon, it's widely available in the US terminal areas though - but then so are decent radar services.
Personally I think stik has a more real world approach to flying and his answer is more appropriate to the UK.