I could do the entire thing, XF import including media gallery and import your photopost data. Setup XF's standard redirects for URLs plus add my additional custom redirects for those they do not cover, add my photophost redirects (no plugin for that, its all in .htaccess), etc. You won't lose content this way or any link rank from Google.
If you do the install first of XF in another folder on your site, for instance,
http://risingsun4x4club.org/xf , then add your logo and any theme changes yourself, that would save you some money, and I could do the everything for $100.
If you need me to do the installation and any theme changes, then it would be $150.
Once everything is verified working, including all redirects, then I'd backup VBulletin, remove it from it's directory and move XF there. (A full backup is also made before I start).
All this assumes you're using Apache (or Litespeed). If you're using NGinx, setting up redirects takes more work and it's $25 extra.
Oh, also, users will not have to change passwords, that is handled by XF's import.
VBulletin would need to be put in offline mode during the import so posts/threads/etc stay consistent and people don't say "hey where did my post I made 2 hours ago on VB go!?!". That's for about 30-60 minutes depending on server speed, and how many attachments users have.
I would need CPanel or ssh access.
If you choose ssh, I'll also need mysql's root user password, so I can setup the database and database user permissions. For Cpanel, I won't need additional access.
Best time to do this is on the morning of your slowest day of the week. Most of my work for my big ongoing clients is on my own schedule, so any weekday ought to be fine. Weekends are a possibility, except tomorrow and Sunday as I've already made commitments.
You wouldn't pay me up front, not until it's live and you're satisfied its working correctly.