Dear there,
I looked into your requirement and found that we can help you in this.
For this we need to following steps:
1) Check product price on listing and details page and if its 0, we need to print link saying "Quote for price"
2) When clicking on that link, it should open one ajax based login window with register link (if not registered customer)
3) Once user login with details, program should send customer and product details to admin with message "Quotation request received and we will contact you soon" at customer end.
4) If user already registered then same process need to follow as above.
Please let me know your feedback and we can start work together.
Kind Regards,
Taha
MoonRose Infotech