Prices vary a lot. Batteries go from about $13 up to $50, with most falling between $25 and $30. Most all replacement batteries are 850 mah (milliamp hours) for the 3G iPods which is more than the original of 630 mah. A couple of companies sell one with 1100 mah capacity which should allow the iPod to play a lot longer between charges. All of them should outperform the original battery.
The tools and instructions vary. Some use metal tools which will likely damage the iPod. For best results, use plastic or nylon tools. Some people say a guitar pick helps. There are good instructions in various places, including iLounge when they reviewed two systems: FastMac's True Power battery and Other World Computing's Newer Technology battery (the second review has better instructions and user comments). The Other World Computing site has a video where the guy does the whole thing in a minute or two. The key is to really study up on everyone's tips and instructions before doing this yourself. Some of the companies will do the replacement for you for about $20-$30 extra.
Other than that it should be about the same. The various options that I found are summarized below. I put the list together in December 2005 originally but have updated it since. Prices are subject to change and there are some suppliers I have missed. I chose to go with Battery Barn which offered a low price, plastic tools, and reasonable shipping rates. They shipped the next business day. The included instructions were the same ones I downloaded from Other World Computing and the battery packaging indicated that it was manufactured only three months earlier (you don't want an old battery). The tools worked just fine and did no damage to the iPod but the tools are definitely disposable since they get pretty torn up in the process. They included two tools, but you really only need one. I won't go into details of how to replace the battery, but it went very smoothly and only took about ten minutes. After a month of use to break in the battery, I measured how long the iPod would play at 50% power and the backlight off. I got 8.1 hours compared to 7.8 hours when the old battery was at its prime, nowhere close to the 30% increase in power I had hoped for, but much better than the 4 hours of the old battery.
|Other World Computing||850 mah||$19.99||$4.50||2 nylon|
|FastMac/TruePower||850 mah||$29.95||free||2 plastic|
|Battery Barn||850 mah||$16.95||$2.00||2 plastic|
|Small Dog Electronics||850 mah||$19.99||$8.00||1 tool|
|Kokopelli Music||850 mah||$19.99*||$6.00||2 nylon tools|
|PDA Smart||1100 mah||$45||free||2 plastic|
|iPod ResQ||850 mah||$24.99||$6.00?||2 tools|
|iPod 911||850 mah||$13.95||free||1 tool|
|L.A. Computer Company||850 mah||$14.95||$9.56||1 tool|
|iPodBattery.com||850 mah||$15.95||$7.00||1 metal|
|BatteryShip.com||850 mah||$9.99||$7.25||2 plastic|
|iPodJuice.com||850 mah||$29.00||$4.00**||1 hard plastic|
|iPodJuice.com||1100 mah||$36.00||$4.00**||1 hard plastic|
|iPod Battery Depot||850 mah||$16.75||$5.75||2 plastic|