Complicated Coding on Orders System - repost

Coding our existing custom coded orders system. The order system has 3 steps that need to be filled in to create the order. 1. for which client the order is created for 2. The order where it is fulfilled and more details this is the project--> 3. changing the way the product is chosen to create the invoice for this order. Now it is created against standard products created in the products page. We need a freetext field product, so we can custom create a field and add an amount for that to invoice it to the client.