In my opinion, most of the time it doesn’t make sense to get paid after the sale for a whole host of reasons.
Here is a list or reasons you don’t get paid:
dishonest client
client forgot to ask the customer
client forgot where the lead came from
client forgot to check the source of the lead
client forgot to record the sale
client forgot to record the source of the sale
client forgot where the lead came from
client forgot where he was supposed to record the sale
client forgot when he was to report the sale
client forget which leads source was supposed to be recorded
client forgot where he put the list of leads he recorded
client forgot what the criteria were for a qualified lead
client forgot to tell the accountant/bookkeeper to write the check
client forgot to mail the check
client forgot the terms of your agreement
client forgot he had an agreement
the client doesn’t have the money right now, will pay later if he doesn’t forget
And those are just some of the reasons I haven’t forgotten about yet.
Another reason is that if your client has zero invested in a lead, he will likely treat it like it is totally worthless right up to the point of getting a sale. If they lose the lead, forget where they put the last batch of leads or accidentally threw them out with the trash when tidying up the office, oh well. It didn’t cost him anything, just “give me more leads and I’ll try not to lose them this time… heh … heh… heh…”
I’m not saying it is impossible to get a client that takes very good care of a lead that personally cost him absolutely nothing, it’s just as rare as the coming of the messiah.
If you charge per lead you are far more likely to get paid for every lead, you won’t have to worry about lead waste or neglect, or the ability of your client to close leads. You get paid upfront and your client is just as invested in the lead source as you are.
By the way, it still can be challenging to get paid on a timely base, but at least it will be clear how much you are to be paid.
Additionally, you need to clearly define what constitutes a qualified lead, put it in writing so there can be no debate after the fact, and always audit the leads returned as “unqualified” before approving a refund/credit. Salespeople have a nasty habit of blaming their own personal failures on the leads after all their sales pitch was perfect, what else could it be, but your nasty ole lead that prevented the sale.