As far as raw drivers go, the Dayton Reference line is probably the most popular choice on Diyma.
Power? This will be my determining factor on whether or not I'm going to recommend these speakers to you. Are you using your stock radio or an aftermarket one? How about an external amplifier?
I'm going to take two approaches here,
1

You're one of those guys with a BMW and wants to replace his stock HK speakers in your 325i, so you came here because you didn't believe anyone on the beamer forums that the RS-150's would work in a car door. Will they? Of course. Hell, it says "excellent car audio midranges" right on the PE page, lmao.
2

You already purchase an aftermarket deck and are pumped to install new speakers. Will they work? Yeah, but hold on here, especially if you're also looking into an external amplifier.
Let's go back to scenario #1. If you're just using your stock head unit and want a simple upgrade, then the RS-150's are an EXCELLENT choice. The sensitivity on them is so high that they are actually louder than my stock speakers. It usually doesn't go this way. First thing people complain about when installing aftermarket speakers to a stock radio is they aren't loud enough. Yeah well how do you know e=mc2. Because I've had 4 of them in my vehicle, IB, for the past 4 months hooked up to my stock head unit.
The freq response says they go down to 40-some hertz. Is this true? Yeah, but the output is VERY limited. You're not going to be shaking any mirrors, but after you see how small the cone is w/ that phase plug, you're going to have a wtf moment. I damaged two of them within the past few months because I ran them with no HPF. I just ordered parts for a simple 1st order X-over. I'm going to try running them at 40hz, just to filter out that last octave and we'll see how they hold up.
HPF of 40hz? Yeah, I'm going to get a TON of **** for telling you that, but yeah I'm recommended a 40hz HPF. Christ guys, he's using OEM H/U power. If by any chance your vehicle has a subwoofer, cross accordingly. You should be able to get away with a 40hz hpf though.
Alright, if you're using an aftermarket head unit and/or amplifier and are planning on running these 2 way and have the room for a true 6.5, buy a different speaker. Why? Excursion. If you're using either of the two, or a combination, then forget about that 40hz x over point. Try 100hz. And if you listen to music real loud, try 125hz.
Plenty of other raw 6.5"s that will work better ASSUMING you have the power and are able to fit them? Is that why you want to purchase the RS-150s? Because you can't fit a true 6.5?
I'll stop there. I've played around with other raw drivers, but I need more info.
Edit: I'm gonna go to bed soon. Here are some other raw 6.5"s that are very popular on here and will work IB and I've used almost all of them
Dayton RS-180 -my first choice. Really a 7" though, and dEEp
SB Acoustics -Get the poly version. There is a paper version on madisound as well. Much better sounding (to me at least) than the other speaker I'm listing next
Silver Flute W17 - $30 a pop. Cheap and some ppl swear by them. These are actually wrapped up in blankets in my foot wells in my GT

Goldwood Polys: Neighbor has these in his BRZ. Cheap, very cheap. Again, more like a 7"
Dayton DC160's -This is more like a subwoofer. Hey some ppl like their mids to dig. Zaph pretty much said this speaker was a POS, lmao. I have this as my logitech sub replacement. My tang band died, lmao and it was layin around so I used it. The owner of PE actually has these in his vehicle and tis not the sante fe either
Well that's pretty much it for under a hundo. You wanna go more then you're looking into SEAS.