Cart Block: checkout validator

I have a few products marked as $0 in my store because I am not permitted to put the pricing online, and even though I customized the "Add to Cart" button to say "Contact for Pricing", people would still click and check out these items at $0 (products have a $4,000-$14,000 value range). This app allowed me to set a rule that products below $1 cannot be checked out and it completely stopped the $0 orders! Took me about 3 minutes to set up once I installed the app, super easy!!