Creating Product Attributes with variable prices

[gtibbetts]

I have virtue mart 3.0.6.  In an older verios of virtue mart I use cart variants to create a drop down of attribute options.  My options include for a primary hard drive the following 250GB; 500GB(+20); 1TB(+30); 2TB(+40);

Here is my problem.  I tried to use type string to create the custom field.  Whe3n I try to set a price for each value it does not let me set a different price for each value.  What type do I use to give each a value a price.  I need the drop down to show up in the cart as cart input.  Let me know what the best way to do this is.