PCI Certificate - PA DSS Validation; the most cost effective way to be validated

We are a developer of a POS system. The POS is not PA DSS validated. We are looking for the most cost effective way to be validated. I have researched the market and found that it would cost us anywhere $8000-30000. We do not want to spend that much cost. Do you know anyways we can reduce the cost of it?

I imagine that someone develop the validated payment module that we can purchase and integrated it.

Any help will be welcomed.

Thanks.