I got my spare 24mm's from Harbor Freight on clearance. Six point is preffered and if you can find one, a breaker bar may come in handy. (you'll see what I mean). I got my breaker bar on a Sunday at an automotive swap meet. Right around closing time they are ready to deal. I went on Friday and it was $22. Picked up the exact NEW breaker bar from the vendor for a whooping $8 Sunday evening.
Autozone has a sale right now on Mobil 1 with a Mobil 1 filter for around $31-$32....but I bet you are an Amsoil kind of guy. I love Amsoil when I can afford it.
My "breaker bar" is a scrap section of pipe from home depot that fits over the handle of my regular socket holder. (They generally have a bin of scraps in the pipe section. Bring your handle and see if anything fits.) IIIRC, it was $3 or 4.
(It's not as elegant as BBB's, but he's a classier guy.)
My breaker bar is a breaker bar because I care too much about my ratchets to slide a pipe over the end. I'm not going to say that I had not done that before but the breaker bar has worked in situations that the pipe/ratchet combo didn't so now I use the breaker all the time when needed.