Yes you can get her still and any money she took from you you'll get back I think.
Getting Yuffie Kisaragi
You can get Yuffie in your party during any disc. If you're in Disc 1 and are riding around in the Buggy, that will work, too. The two places that she appears most often are the forests beyond the Gold Saucer (in the Gongaga Area), and most forests in the Junon Area. After a few battles, you'll fight Yuffie (seems to be a 1 in 15 chance, if you ask me).

Just attack her, really. Yuffie can use all kinds of cool attacks during this time, but not once she joins you! Yuffie's level, HP and MP vary depending on what level your characters are at.

When the battle ends, you'll be in a plain with Yuffie lying nearby. There's also a Save Point here. However, if you touch the Save Point, then go to your menu screen to save, Yuffie escapes and steals 200 gil! Don't worry, you can meet her again. You'll have to talk to her several times to get her to join. As she and you converse, she'll ask you several questions, and you can reply in two ways. To get her to join, respond like this:

Reply: Not interested

(talk to her again)

Reply: ......petrified
Reply: Wait a second!
Reply: ......That's right.
Reply: ......Let's hurry on.

Or in other words, choose the bottom reply, then the top one, then the bottom one, and so on. After that, you can name her, and she'll hook up with Cloud and the rest of the gang. Note that if you choose the top answer for the last question she asks, you can name her, but she'll steal 700 gil from you and run away. You'll have to repeat the whole process if you want to get her in your party.

And the pass word is Right to 36, Left to 10, Right to 59, Right to 97