I've had a LONG run of possible buyers who exhibited every buying signal, knew my rates then dropped out just before the deal closed. Is it something in the air? It's never been like this before.
There are many ways to approach this.
1) Set high fees, so only successful, well informed folks inquire.
2) Never haggle. Period.
3) Charge for client vetting/onboarding + name your offer something spiffy... like...
4) Advanced Practice: Have no front facing Website, so only direct referrals even know you exist.
I run a high traffic, high speed, private WordPress hosting service.
Recently a buddy of mine suggested I monetize my onboarding + his suggestion was good.
Now I'm doing Website audits, which I use to do for free, for $497 + affiliates who mail/promote my service are paid 50%.
So, I pay $0 for unlimited leads (OPML - Other People's Mailing Lists) + $0 for lead technology like mailing + then make $150 for every new lead... so think about this...
Every new lead pays me $150 each, so my lead generation is now a profit center, rather than time drain.
Try some variation of this where you...
Roll up your common practices/questions/activities related to onboarding into a sale or fixed priced (one shot) offering.