If you're in the UK, then you can use Topcashback [1] or Quidco [2]. Both of these links are affiliate links too, so if you start receiving cashback then I'll get £20.

With both of these services, you get to collect the affiliate fee. Some things like insurance are huge and you can easily get £100 for them, most are much smaller.

1. https://www.topcashback.co.uk/ref/aembleton

2. https://www.quidco.com/raf/23003/