magento development and setup freelance

Hi, we are finish the testing of a web site based on Magento 1.9 version. we need per hour and continuos improvement with new functionality, exensions and additional parametrization support. Our products final price is based on: (cost + cost * %_per_supplier)*vat Where %_per_supplier is the % we have to apply to each supplier product. That % is defined in the Supplier table. for example: Supplier 1=40% Supplier 2=30% VAT=fixed= 20% Supplier 1 supplies product A and B with A cost=100 and B cost=200 Supplier 2 supplies just product C C Cost= 300 Product A final price=(100+100*40%)* 20% Product B final price=(200+200*40%)* 20% Product C final price=(300+ 300*30%)* 20% For all cases the cost is the one coming in the Purchase´s Order generated from the ERP. Be aware that this cost is not the standard product Magento's COST attribute/field based on the fact that we don't use the weighted average cost which is the default cost calculation method.