Bluetooth speakers in vehicle

I was fishing around for information previously concerning the crap sounding stereo in our new 2015 Tacoma. Due to unforeseen recent events, I am changing direction on trying to replace speakers, add an amp, etc. Money just really tightened up for me and budget is extremely limited.
I am now looking at a Bluetooth speaker that I can use as an alternative to running the stock stereo speakers. I primarily run my cell for stereo as the sound is usually better than head-unit FM and XM radio. Perhaps this is an un-thought-of option but I am thinking "run cell music to a great sounding bluetooth speaker and put it in the back seat to fill the truck with sound.
Has anyone done this, which speaker did you use and what is your experience good or bad.
I have looked at the Brookstone Big Blue Party, the Jawbone Big Jambox (starting to hear quality issues with the BJam) and the Bose Soundlink.
Please provide any input if you have it relative to this topic.
Thanks and LOVIN' the new TAC.
TomBow