Pro Sites - Setup Fee / Upfront fee option

I just want to add a suggestion for an option in Support to charge a setup fee / upfront fee in addition to the monthly fee.

Some users manually do some setup work for new customers, others want to charge it to make their site more profitable or to compensate for marketing expenses, or to make promoting the sites more attractive to affiliates. I know that's a feature I was looking for and the only way to do it currently is in conjunction with the Membership plugin, which doesn't support the same payment gateways, and isn't ideal since the Membership functionality really isn't needed other than taking a separate upfront payment.

This has been asked about and requested quite a few times before, but not in the Featured Suggestions & Feedback category, so I just wanted to make a central thread for this discussion.

Here are related posts where users have asked for this:

https://premium.wpmudev.org/forums/topic/is-this-possible-with-membership-and-or-marketpress#post-96073
https://premium.wpmudev.org/forums/topic/pro-sites-specific-price-options-renewals-setups-etc#post-227323
https://premium.wpmudev.org/forums/topic/details-about-membership-prosites#post-175060
https://premium.wpmudev.org/forums/topic/simple-modification-to-supporter#post-43807
https://premium.wpmudev.org/forums/topic/setup-charge#post-194188
https://premium.wpmudev.org/forums/topic/1-for-a-prosites-upfrontstratup-payment-on-sign-up#post-176481