A lot of companies sell their laptops straight from the website itself, and often allows customization options. From time to time, you can find options that will allow you to have Windows 7 preinstalled, but usually at an extra cost. I remember reading somewhere that a company did in fact revert to having W7 preinstalled, rather than W8, though the name escapes me now.
As for your battery issue, there is a pretty good chance that a battery wouldn't cost the same as a laptop, unless you got your laptop for 100-300 dollars, which is the average prince range on laptop batteries depending on what type of battery you get, e.g. 6-cell, 9-cell, 12-cell, etc.
Another thing I'd like to mention is that W8 really isn't that bad. I recently purchased the newest model of the Samsung ATIV Book 9 Plus, which runs Windows 8 preinstalled, and though there is a bit of a learning curve, I learned to adapt, and I actually kind of like it.
Good luck!