Material brokerage and erpnext

We are a company who deals in bearings and bearing housings. However, we are a brokerage, connecting customer/client comments to the bearings they need at the best prices possibly by purchasing on their behalf from different suppliers.

A typical stockist might have an inventory running to tens of thousands of items. We have no inventory. Additionally, our clients know precisely what they want, because they know their own business and requirements.

So my problem is how to create RFQ, quotation, invoice etc. forms which have multi-line, free-form item fields which can be filled in without requiring a list of predefined items. Is this even possible ??