It is a common knowledge that it's a good idea to create a network of buyers / investors when one does wholesaling, in advance . So that when a wholesaler has a property to assign or to sell, he/she doesn't have to waste time when the time is of the essence, and the whole transaction is on the line.
It also has been suggested that a wholesaler needs to be sure that his buyers are what they say they are, in terms of their ability to close, i.e. their finances, credit, etc.

Question:
When the wholesalers first create that network of buyers / investors, HOW TO CONFIRM THE PROSPECTIVE BUYERS' FINANCIAL CAPABILITIES?
I mean confirm INDEPENDENTLY, since simple asking doesn't do it.
Note: We are discussing buyers / investors, NOT retail buyers.

Work with a lender they will qualify them for free and you won't waste your time.If it's a cash investor have them supply a copy from the bank that they have cash funds to purchase.

I would be interested in the answer to my question: How to check the investor/ buyer BEFORE the wholesaler contracts for the property and tries to sell or assign it.
NOT when it's under contract, the wholesaler is looking for a buyer, and time is of the essense.
The answer above, also is correct, but is not the answer to my question.

I guess i don't get your question.I have about 40 investors that have gone through a qualifying process with me and the lender or have shown proof they can pay cash.When a deal comes along or i assign something i already know if they like the deal they can jump on it and are credible.Example a mortgage broker tells me x investor can buy in 120k to 140k range.Great i break them into groups and segments so i know who to call with a particular deal.

There doesn't have to be a contract or a deal before you can qualify them.There are always risks peoples situation changes and some can fall through.You word the contract so that you have out clauses and don't have to purchase the property.

I already have groups of people qualified so when a deal comes along i'm ready to go.

If all you are getting is mortgage brokers saying when you have a contract i will qualify them,dump the mortgage broker they aren't in your best interests.

To super realtor:
Thanks.
Your answer is closer to my original question than we both thought.
So, HOW DO YOU QUALIFY THESE PROSPECTIVE INVESTORS / BUYERS ORIGINALLY, WHEN YOU FIRST SELECT THEM INTO YOUR NETWORK OF BUYERS ?
What do you actually do, or ask them to do, or submit to you in order to qualify them?
Again, it's at the time you don't have anything for them YET, but would like to consider these buyers in the future, when you find properties.

Ask them how many deals they have done, how long in the business, and under what name or entity do they hold title to their properties in... Then go to the courthouse and see if their story checks out. If they say they have bought 50 houses over the last 10 years in the name "John Doe Properties, LLC" then it is easy to see if John Doe properties shows up in Public Records or not and how often.

Most lie about their experience in my experience.

type of property, location, price points, after repair value, how much below market value

if youre on the mortgage side, run their credit.