Small purchases: lots of pegs. Way more than you think you need. I always have loads and still run out on those sunny days when you wash everything in the house.
Bumper packs of: foil, clingfilm, plastic bags, greaseproof paper. Throw all your Tupperware out and buy new ones that all have lids.
12 teaspoons.
12 white flannels.
Do you have to hand - good scissors, plenty of sellotape, envelopes, all-purpose greetings cards, paracetamol/Calpol, plasters, micropore tape, spare toothbrushes, bobbles, a lint brush, decent coat hangers, bags that fit your bins, etc etc?
In short you could spend maybe £100 but sort out every tiny annoyance in the course of a day. I did this once and it was so worth it!