"Put a liquidated damages clause in your specifications or request for proposal, then when invoiced for the late parts, pay the only the reduced amount based on your RFQ. Just be careful, if the LD's are too high, they will start factoring it into the price."
Very common in the construction industry, especially public works contracts.
Four issues come to mind:
One, you may find suppliers/contractors that simply won't agree to that, if they don't normally deal with such requirements.
Two, as I understand the laws, a liquidated damages clause has to bear some resemblance to actual damages incurred, and can't just be a penalty clause. Speaking of which, if you do incur costs from delay, it's just as reasonable to include a bonus for early delivery as well.
Three, whether high or low, the LD should be factored into the price, unless the supplier is pretty sure there is zero chance of delay.
Fourth, in some cases, it simply may not be reasonable to saddle the supplier with the LD amounts that are appropriate. If you have the million dollar contract, and you want the hardware store to guarantee they'll have your bolt tomorrow or pay you $10,000 a day until they do, you're not likely to find a hardware store to agree to that. In that case, the purchaser has to assume that risk rather than the supplier.