Maybe something like '' This quote is good for 30 days, product not scheduled to be shipped in 30 days is subject to a xx% price adjustment''
A quick story. I did about 500 pieces for a customer at $1.80 each, he wanted 120 of them shipped in 30 days. I still have the balance (along with my profit) sitting on the shelf for 2 years. The good news is that the 120 pieces covered my cost for materials.