If you have an iPhone, I use a combination of two apps to track the growth and value of my card collection - Pokellector and Ace Pokecard. Both are available for free on the app store.
If you don't have a smartphone, I also use store.tcgplayer.com/collection. It's the most comprehensive one, as it lets you map what cards you have, and computes the value of your collection for you as well.
As for the price of the base set, it honestly depends. For a complete, mint, base set collection, I would say $500 is a fairly reasonable price, although you would pay $100 - $200 less by buying each individual card. You can buy them on coolstuffinc.com, which has by far the lowest price for quality cards. If you would rather see the cards before you buy them, google game stores in your area that carry collectible trading cards - they'll help you out, although you'll pay more than you would online.
Talk to your daughter and see what she wants. She may want only the newer cards, or she may want to pick and choose each card. I'm not a complete collection collector - I prefer to cherry pick each and every card that goes into my collection, besides the ones I get from booster packs. On that note, she may only want to get the booster packs - getting a rare card through the luck of the draw is immensely satisfying, and is one of my favorite parts of collecting.
Beyond base set, the original series is comprised of the Fossil, Jungle, Base set 2, Team Rocket, Gym Heroes, and Gym Challengers. There are also the Wizard Promo Cards, which aren't as well known, but are fabulous.
Let your daughter take charge of her collection. Teach her how to organize it, store it, track it, and research new cards, and then let her do her own thing. A collection like this, that she's starting at a young age, will be something she takes pride in for the rest of her life - let her put the time and work into it.
Good luck to you and your daughter! I hope you both enjoy the collecting experience.