Configuring multiple options with multiple customer levels?

I'm having trouble figuring out a good way to set up some products for my brother in law's store.

The scenario is that we have a product that is sold in 6 different sizes, each more expensive than the last.

1 gallon: $10
5 gallon: $40
etc etc.

We also have 5 customer levels. Full retail, level 1 thru level 4. Each get's a different price. the issue I have is that when I set up the options for the product there is no way to set up the price for each level as well. This appears to only be possible on the main price entered for the product (retail).

At this point the only obvious solution to me is to create a unique product for each size so that we can apply the customer level pricing properly. I've searched through the extensions and the forums and can't seem to find an answer to the problem. If there is one.