dc42:
You can get 0.1% tolerance resistors quite easily and cheaply, especially if you are prepared to use SMD components.
I see Digikey has quite a good selection of through-hole ±0.1% resistors for 55 cents each / 42 cents each at 10 / 6 cents each for 5000. Prices come down quite a bit if you need a a pile. Just search 'Resistors' and modify the search criteria ("parametric search") for ±0.1% tolerance