Actually like DSPatrick suggests you should look into USMT.
But if you have $1 per PC then for the above project I think you should look into User Profile Central (UPC) from EhlerTech.
- Ehlertech is a one person company specializing in user profile migrations.
User Profile Central is basically just using USMT but can push USMT to every client, and then runs it remotely.
The whole process, selection of users, and what to migrate is setup in the UPC interface. Data is stored on a network share on the domain
You only need to install User Profile Central on one Technicians PC's on each domain.
From there you can run a user profile backup on all the PC's.
Move over the backups to the new domain and restore to the new PC's
One thing: You will need a Domain user who is local Admin on all PC's.