Vendors portal script

Good day,

Our company sells dairy products and would like to create a portal where certain resellers can login and place orders.

Website should no show pricing on products unless the reseller is logged in.

The script must have the ability to export to a customized csv or txt file that we can download and import into our erp system.

What would be the best cms with plugins or mods to create a system like this?

Thanks in advance

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