cheap instant coffee is just vile. must have decent coffee, choc and wine - less often but better!
good quality bread, muesli, cheese, sauces, toiletries, candles, pens, shoes/boots, glasses, bedding, all make life a little nicer, esp if you get them as a bargain.
cheap towels. go hard and bobbly faster. i invested in some lovely ones (can't remember if JLewis or M&S) about 6 years ago and they are still lovely!
as well as good bed/mattress as said before, i would also recommend getting the best sofa you can that suits you, my one is supercomfy and well worth it as i park myself on it every evening.
i buy one lovely notebook about once every 6 months for my lists-obsession, but it makes me smile every time i take it out and open it, its a visual and aesthetic joy and one of the things that makes me feel good about life.