I have been working with a client to setup an Ubercart store customized to their needs and one of the things we came across as we launched the store is that because of the nature of the items being sold, it was very difficult to give a accurate shipping estimate. Thus, I set off to find a way to enable customer payments after checkout and to enter the shipping quotes manually.
These two modules, uc_manual_shipping and uc_payafter, are the fruit of these efforts. I hope you find them useful!
Note that this is my first release of these modules and the code should be considered a beta and work in progress. They are untested so far and not recommended for use on a production site just yet. All information about installation, configuration and further development is available in the README.txt file, DEVELOPERS.txt file and/or source code comments. If you have made some changes or improvements, please let me know in the comments! I would love to hear about your changes and I would be more than happy to apply any patches or bugfixes.
uc_manual_shipping enables the store administrators to manually enter shipping quotes on orders after a user has passed through checkout. It can be used in combination with uc_payafter to have users create go through regular checkout without paying, and then pay later once a shipping quote has been submitted by a store administrator.
uc_payafter duplicates the checkout process and allows users to perform payments on their orders after checkout at the URL cart/checkout/pay/$ORDER_ID. Store administrators can email users different invoice templates after payment.
Update 2011-06-08: A user in the comments, Moises, has pointed out that in the 6.x-1.0 release of uc_payafter there was a typo that would prevent users from being able to select the request shipping invoices in the conditional actions configuration. I have updated uc_payafter below to fix this bug.
Update 2011-11-08: uc_payafter has a new home! I have created a Drupal Sandbox project for the code here. Once I have the chance to work on the code a bit more, I will promote it to full project status and update the download links in this post.