Hands tied re: Trans Fluid change? Advice needed

[jdlamoreaux]

I have a 2007 Yaris Sedan with 197k miles, automatic trans. Original owner. Serviced with the dealer for the first 7 yrs, then I just took it to some random local garage that seemed pretty honest. They closed down so I tried another place for my last normal maintenance. They told me the trans fluid is dirty and should be changed out ASAP, cost of $300. Problem is, this is the first time I remember even talking about trans fluid (I know next to nothing about car maintenance, I've always just had to trust dealer/mechanic). So I don't know that it was ever changed. And $300 seemed steep. There are local auto repair chains that do a trans flush for $129 so I took it there and they told me just so I'm aware, Toyota says not to change the trans fluid under normal driving conditions for the life of the car. So I decided not to mess with it yet.

Do I risk damaging the transmission at this point in the life of my car by flushing the fluid? Also, why do the small garages in town charge $300 and the chains charge $130?

I'm just totally confused at this point. Any help appreciated!!