You aren't going to get a decent laptop running windows for under $300. If you find a new one that is less than $300, it won't be any better than what you have now. What program do you use for car diagnostics? There may be an equivalent on Chrome OS.
Its called FlashProManager it is more of a tuning/diagnostic OBDII thing. Very low req. I found one at best buy that was $249, it was running well with a touch screen. Just figured I would ask before spending the cash on it.
I don't see WoW running on that laptop at past low settings at playable rates. If you really only have a $300 budget and want something that will play WoW or games in that range, you need to look at a used laptop.
Since WoW came out, it had a lot of video updates and requires a much faster system to run. The new expansion pack coming out will be even harder on systems as they are upgrading the character models.
For a laptop to have a touchscreen at that price point, or ANY laptop at the price, you are looking at something that is really compromised for cost, small screen is one thing here, a low power CPU is another.