If the vendors are changing it for you for $299, they may be misunderstanding you. The compilot battery service is available at most shops for about $130 (parts and labor). $299 is the retail price of the entire compilot device. This is something you have to send your compilot in for, it is not meant to be user serviceable. Most vendors charge for the battery and an average fee of $125-150 for install, so you may want to check that they are understanding you want the battery only.
If your unit needs to be serviced for other reasons, you can also get a flat rate repair service: http://amzn.to/1QFFezh
While the battery cost may seem excessive, it is custom made for your product and has no other use, meaning limited production runs and higher costs for custom manufacturing. It is also designed to last through several years of all day long daily use and multiple recharge cycles without losing capacity, until it reaches its end of life stage. That is not something that can be said for most batteries. The compiliot is a premium product, and just as a luxury car needs premium gas and more costly tires, the premium health products like this have more costly maintenance needs as well. 2 years is the intended service life of the batteries, which works out to about 18 cents a day.
If you want to try another vendor, I'd recommend the same vendor as above, whom you can reach at(###) ###-####/p>
Best regards, ***** ***** for the news,