You can use differenct prices for different customers By using Tier price. It is usefull when we have product which sale in different price for differenct group of customer like wholesalar, distributor or General.

Also Tier price usefull for offers on product depend on quantity.
EX. Product price 6000
Group QTY price
Wholsale 8 5000
Retailer 10 4500

Please follow below steps.

2. You can set special price, Customer Group price and Tier price for product based on customer group and QTY.
3. Also assign customer groups to customers.
4. On order form, whatever price you assigned to product (depending on customer group and qty )  will reflect.