Nico Nico Nii!~
My first question for you is, how long has your daughter been collecting? The Base Set was released in 1999 and last printed in 2000/2001, so knowing how long your daughter has been collecting would help determine whether it's actually the Base Set that she has or some other set. If she's only recently started within the last year, it's probably not the Base Set she is collecting, especially if she's under 12. I don't want to see you spending big money on cards she won't recognize when a still-in-print set will make her much happier.
As for the collection tracking stuff, there's a few Excel spreadsheets around the Pokemon Trading Card Game section of this forum somewhere that people have created to keep track of the stuff, but I've not got the time right now to go digging.