Why the frick would you want a 4 way speaker? Its a gimmick. Dont waste your money. I'd also recommend not buying from crutchfield, they overcharge horrendously. Thats like buying all of your parts at autozone instead of rockauto.com.
A good bet is from woofersetc. Pretty good prices, not the greatest site layout for people who dont know what they are looking for though. My personal recommendation if you arent upgrading anything but the front speakers, would be...
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=6380 since its closer in line with the amount of power you will actually be sending it. It's not good to under power speakers, leads to turning up the volume to the point of distortion. That would be probably the best choice, and one of the cheapest as well.
I stuck with a pioneer product only because I assume you are comfortable with them as a brand. Dont get a gimicky 3 or 4 way speaker though, just leads to harsh tinny highs from edge driven psuedotweeters. (yes i made that word up, its what i call any sort of "super tweeter" that is put in for gimick sake)
You have essentially nothing to gain with getting anything nicer than that. Now, should you decide to get a small 2 channel amplifier or something along those lines, theres plenty of better options, but the best you can do to make your stereo sound better, is going to be to seal up your front doors as best you can, and replacing the stock speakers with near oem spec replacements.
Any aftermarket speaker thats worth anything is going to sound much much nicer than the 10-20 year old stock stuff thats in there now. But volume isnt derived from the speaker, no point in getting something that wants 90 watts to operate correctly when you can barely send it 20.
Save your money! If anything, save your money for a small 2 channel amp with high level inputs.
