Wouldn't you just print out a difference spec instead of the standard requisition form, print out one that says "RFQ" and you adjust that crystal spec to just show the fields you want to print?

We did one that does essentially what Eva is suggesting - but the PO is a Standing PO to an internal vendor with no prices; then, when they print, it prompts for a vendor code (or multiple codes).  Name and address of selected vendors print on the RFQ so it can be sent to those vendors.  When the PO is awarded, they create a live PO from the standing PO for the winning vendor and fill in prices.