Options Set-Up Help

I am a little confused on how to set up the following scenario:

1) Some floral products we carry have several options associated with them.

Here's a scenario:

a) The main product.
b) 15 Colors to choose from

Pricing is as follows (2 Customer Groups / Retail & Wholesale):

Single Price: $18.95 each (Retail Group)
Case Price (12 in a case): $18.00 each (Retail group)

But some of the options "base single price" is $35.95 (not $18.95)

So if you buy "less than 12" the single price would be $35.95 each

But if you order "13 or more" the price is $34.15 each

So, the MAIN QUESTION is if I set the "base price" for the product at $18.95 - if they order the higher priced option of the product - how do I set this product up correctly in the admin area to work like the scenario above?

I hope this made sense.

Standing by...

OC 1.5

Respectfully,
Leonard Michael