One approach you might use is to have a referral price. No, not a commission on the referrals you receive.

You are negotiating a deal with a prospect that you know has links with many other prospective customers (government departments are a prime example). You are stuck on price (need to produce a BAFO (Best and Final Offer) here in the UK. Offer them a lower price if they commit to giving you a number of qualified referrals over the next 12 months. Your contract needs to stipulate that the balance of the original price is payable should you not receive the agreed referrals.

Note, the deal is to give you referrals - there is no guarantee of getting additional customers.

It works. You probably won't lower your price more than you would have had to do to get the business anyway. And you get the concept of referrals in your prospect's mind.