Materials Discount multiple location national account

I own a national education and coaching company. I would like to set up pricing accounts to help all my past clients get deep discounts from volume buying. We have 60-80 contractors per year and believe if we combine our past clients it would give more purchasing power.

Need to discuss how to pay on this....

Home Depot

Lowes

ABC Supply

Floor Decor

Electrical Supply House

Equipment

materials

etc