I agree with most of what Webbage said. However, I would reccomend the maxamps.com 2000 mah 3S LiPo battery. It's got a much smaller footprint than most of the 1320-1500 stuff out there, and its a stronger battery. Webage is right in that 1000 mah is plenty of battery, BUT, most of the smaller mah batteries don't have a high enough C rating to keep up with the high power brushed or brushless motors, and have problems with overheating and they don't let your power system live up to its full potential.
When I got started, I was strictly brushless and LiPo. I've run two Novak Goat brushless systems, and a Holmes Hobbies revolver and crawlmaster outrunner brushless motors. You can say that I've run the gammet with brushless systems, strictly because I didn't know a lot about crawling and didn't want to go with old school technology. I will tell you this, I was WRONG. The first time that I ran a cobalt puller, both of my Novak Goats when up for sale and I went strictly to Mamba Max ESC's with high power brushed motors. The Cobalt Puller is twice as powerful as any of the brushless setups that I ran, it's way smoother, you can volt up and gear it down lower for smoother low end throttle response, and it has more wheelspeed at the same time.
The brushless outrunner motors are going to give you tons of problems with cogging, especially, with the mamba max or sidewinder ESC. If you're going to go the brushless outrunner route, the castle ESC's are not the best route to go. The combo is really bad about cogging. If you run the outrunner motors, you need to have a Quark Pro Car 33 ESC, which you will be able to find used.
I can't say it enough, you wont find a brushless system that preforms half as well as the right brushed combination. I know where you're coming from, as I was striclty brushless and LiPo, but once faced with the facts, I had to admit I was completely wrong. Also, you aren't going to be replacing brushes with these high end Holmes Hobbies motors. Most guys run them for years and get a new motor before they ever need brushes. I would say at least 90 percent of the crawlers out there running brushed motors, have never worn out the brushes in a motor.
You WILL need an external
BEC with the Mamba Max ESC. The stock Mamba Max ESC only puts out 5.1 volts at about 2-3 amps (I believe) which when combined with a high torque servo that you need for crawling, will cause your motor to cut out when you turn the wheels and pull throttle. The Castle external
BEC can be set at 6 volts and will run up to 10 amps. If you want to talk to someone who went through weeks of headaches because they didn't have an external
BEC with a Castle ESC, talk to "SlowNGreen". He had hell with his system.
If you can afford it, I highly reccomend the Mamba Max over the Sidewinder ESC. It's made of better internal components to run at higher voltages, and will handle 4S LiPo a lot better if you decide to bump it up one day and gear down. The Mamba's are also a lot better about being water resistant, and the price of the Sidewinder and Castle Link programmer together are just a slight bit less than the Mamba Max.
When choosing your battery, you need to be thinking about size. I don't know of a 1500 that will fit in the spaces where you need to put them on your crawler, which is why I mentioned it. The maxamps.com 2000 mah 3S LiPo has the best footprint that I've found, and if you want some other reccomendations I can help you out.
John Robert Holmes has his motors built with standard 540 size pinion shafts, and you can buy the set of pinions with 9-13 tooth (which is what you'll need) in 48 pitch for about 20 bucks. I would try to stick with those pinions as they're cheap and work with the 48 pitch spur gears.
