That's all good.  Just throwing it out there.  I did the same thing.  And the $'s added quickly.  Will never get out of it what was put in.  Not sure if I would do it again.  But sure don't regret it.
Sounds like it will be a great project with the kids.
Good luck and have fun with the project when you find one.  They are out there, but you are right, too many think they are worth gold because someone told them so.
AZ