Allow your users to complete checkout as soon as minimum cart products quantity criteria match or prevent them buying beyond maximum allowed quantities. You can also define cart total or Sub-total threshold to ensure minimum purchase amount must be satisfied.

Prevent users to checkout without meeting minimum criteria 

1. Cart products quantity 

2. Cart total/sub-total  

Example: 

(minimum quantity = 2) OR (subtotal >= 200usd) for wholesaler 1 laptop (50usd), 

1 imac (50usd) = 2 items & value less than 200USD; OK 

1 server (250usd) = 1 item & value more than 200USD;

OK 1 laptop (50USD) = 1 item & values less than 200USD; Not OK 

1 laptop (50usd), 1 server (250USD) = 2 items & value more than 200USD; OK 

For example, thanks to ** Alexander Johansen **  

Checkout Rules are based on Customer Groups hence it’s give you flexibility to define separate criteria for each customer groups. And for convenience *Customizable Warning Message* for each language installed on your Opencart store plus for each active currency you can set unique values.

Customer Group - Default

Email : default@test.com

pass : default

Customer Group - wholeseller

Email : wholeseller@test.com

pass : wholeseller