Look at AR Terms Codes, which are not done at the line level, but are close to what you seem to want.

Thanks for the quick feedback. The terms code looks like it is close to what I need, but we offer different discounts on different product lines within the same price level. As an example, Price level 1 gets 10% off of product line A and 5% off of product line B. I don't think this can be accomplished with terms codes. Am I misguided?

Thanks for the quick feedback. The terms code looks like it is close to what I need, but we offer different discounts on different product lines within the same price level. As an example, Price level 1 gets 10% off of product line A and 5% off of product line B. I don't think this can be accomplished with terms codes. Am I misguided?

Correct. 

Line level discounts cannot be automatically reversed after a certain date.  That is how terms work (give the discount only if paid on time)... but only at an invoice level.