price matrix and calculator

[blackhorse]

I am looking for an open source system.

1) set up the price matrix in the admin.
2) in the public page, a price calculator (such as pick up from 1, 2, 3 years contract, and pick up from gold, silver services, add the additional package, count the discount, the total price would show)

It is not so difficult to write it from scratch, just want to see if there is an open source can save me time.

If there is not, maybe it would be a good project for open source.

Thanks!