I used to use the rule of rebalance = 2/3rd full set price so I was £30 full set and £20 rebalance.
But I am putting my prices up, full sets have gone up £5 but after much deliberation I have decided to keep the same price for rebalances so as my price increase doesnt affect my v. loyal regulars as much. What I have done is drop the 2 free replacement tips I used to include in the rebalance price and I will now charge for each replacement. The majority my regulars look after their nails and it is a very rare occassion that any of need a replacement tip, so the change in pricing will be an incentive for clients who dont look after them.
My new prices are
£35 full set = £20 rebalance = £3.50 replacement nail
£40 full set glitter work = £25 rebalance = £4 replacement nail
I dont have a different price for natural - never been asked for it, the most natural my clients will go is soft white Brisa.
HTH
KxXx