There are a number of threads on this if you do a search. I guess it all depends on your budget and time. Mirrors are generally easy to replace if there's no body damage. I haven't needed to do my Rav4, but I have replaced on other cars easily.
Here's a link (courtesy of JuneBug's post back in 2010) with a pdf on how to replace mirrors. http://www.rav4world.com/pdf/Mirror_removal.pdf
You can judge from that if you want to DIY. Then you have to look into OEM vs aftermarket mirrors (and how one matches up to your driver side.) Others might chime in on their experiences there.
Good luck and thanks for your service!