Ideas on collecting payment before form submission? I have a use case in which I wish to collect payments before users are allowed to fill a form; basically the form is an assessment form for which the provider (offering analysis) would like to charge money.
Currently I have the form setup using webforms, but I couldn't find a decent or well established way of collecting payment with webform submission. I already have Ubercart on the site so, if there is a Ubercart to webform bridge, I would definitely like to know about it as well (I couldn't find any). Lastly I am also open for any other approaches. 

My use case is the following.
Users pay for the assessment (service) using Paypal, and then they are given a link to submit a form; the submitted data need to go to the provider.
Do you have any ideas on how this could be implemented? I assume it should be a relatively common use case.
Have you tried the Ubercart Webform Checkout Pane module?
You could define a simple product and use the webform as part of the checkout process.
Some more details about this module (from its project page):

This module allows you to define Webform nodes as checkout/order panes in Ubercart.
This is useful if you want to collect additional information during the checkout process. For example, you may want a quick survey or require additional fields that apply to the entire order.
Using the Webform module allows for many advantages: the forms/fields can easily be modified by an end-user; less development time is required to create database tables and code to store/retrieve the data; and the form will remember the user's previous answers.
Furthermore, this module now provides tokens for every field in each of your enabled webforms, making it easy for you to insert the submitted values into confirmation emails, invoices, etc.