Pricing calculator

I am looking to develop a very simple pricing spreadsheet. What I need is a cell where a value (capacity) can be entered and a and price outputted based on a tiered pricing structure.

For example:
band 1 - 0 to 99 (price rate $0.007)
band 2 - 100 to 299 (price rate $0.005)
band 3 - 300 to 599 (price rate $0.003)
band 4 - 600 to 999 (price rate $0.002)
band 5 - 1000 and beyond (price rate $0.001)

If I was to select a value of 650, the calculator must blend band 1, band 2, band 3 and band 4 based on each band to calculate the price (differential equation?) for any given scenario through each band. Its not a difficult calculation process but I also need it to be user friendly but to also have seperate pricing band in order to to the calculation. Plus it must be easy to maintain when if the pricing bands need to change.