Pshaww, let me end your search here. The Soundfreaq Soundkick is honestly the best speaker for the money out there. It is bluetooth, and has an aux input (3.5mm), and can even charge your phone on the go (as long as you're playing music below a certain volume level). It also has an app for both Android and Apple that acts as a remote control, although it is in need of help (they say they're updating it soon). But honestly, it is one of the best additions to my tech ever. It is so portable, the sound is great, it is very loud for it's size. Just great. Check it out.
Oh, and the best part. It's $100
Now, if you have a little more to your budget (unlike I did lol), I'd highly recommend the Bose Soundlink II. Last time I was in Miami, I got off the plane and basically went to the mall with my carry on, which happened to have my Soundkick in it. I walked by the Bose store and saw them advertising their new bluetooth speaker, the Soundlink II, which also had an aux input (3.5 mm jack). I whipped my Soundkick out and made some comparisons. That thing was AMAZING. It was so loud, yet music didn't get distorted. It looked almost as portable as my Soundkick (slightly larger), but the biggest thing was the sound. Apparently it has eight speakers within it (don't quote me), two of which are on the BACK of the speaker (quote me on that one, I remember that to this day haha). Anyway, long story short, that thing was amazing. It was also $300. So those are the two best on the spectrum of budget in my opinion. Hope I helped you out a bit!