Whether it's an athame, besom, tarot deck, cauldron, or any other tool, you should take your time finding it. I remember quite well the initial excitement of shopping for magickal tools when I first began to practice again a few years ago. I was eager to find everything I "needed" ASAP. I didn't make that wise choice at first, when I bought my first deck of tarot cards. I didn't wait for a good deck to find me, I just bought one. It actually sort of worked out, though. It was one of those beginner decks that were super cheap at some bookstore in the mall, and it came with a decent little book that gave me some familiarity with spreads and the card meanings. They were mostly just to play around with for a while, until I became more comfortable.
I'm trying really hard not to ramble about myself much, and this is the third time I've edited this in the past two days, trying to make it make sense. I've been keeping very weird hours because I'm caring for Munchkin (the kitten I'm bottle feeding), and I'm absolutely exhausted.
When you find a tool that's right for you, chances are you'll feel it. Plenty of items may catch your eye, but if you ever pick up something (say a pendulum) and feel a tingle, a jolt, or just an instant connection (or your feeling may be different, these are just a few examples I've heard to describe the feeling), that's probably the right magickal item for you. If you just find something that you think is pretty and you don't feel any connection to it, it may still work out for you, but the connection may not be as strong.
There's no reason to just rush out and buy up all the magickal tools you can find in one day. You may find that you don't even use those things after a while, or at all after you get them home. If you feel that you really must have an athame, a besom, a chalice, a wand, a cauldron, etc., by all means get them! Just keep in mind that your tools are special and should be selected carefully. You wouldn't just walk down the street and invite the first stranger you see to a ritual would you? If you use your tools regularly, you form a bond with them in a way, just as you do with people (though it's a different type of bond). There's no need to rush finding tools for rituals; it's perfectly fine to do rituals without tools, at least until you find the ones that are right for you (that is assuming that you feel the need for them at all).