Any compensation is meaningless because the people who benefited from the faulty update going live will also receive the compensation. Just write off the whole thing and try to be a little more professional next time. You should have either caught the error which people knew about hours in advance or else just left it alone. Causing mass outrage to maybe make a few $$ in the future off people buying those ninjas for somewhat higher prices is a poorly thought-out strategy. The only way to really fix the issue is return the prices and items for the rest of the week and give everyone a chance to benefit from them.