Is this a good match? Amp and sub?
 

I have a L7 dual voice at 4 ohms w/ 750rms and 1500 peak. I am getting a Alpine mrx m100 that was used for a week when my friend lost his license. He is also giving me the bass knob which is alpine and still in the package. He sold it to me for 225$ . I have my L7 wired for 2 ohms so will get 1000watts from amp. What do think? Good match? My woofer is 1500 peak and amp 1000max so feel I could have used a bigger amp.

That amp would be fine, just make sure you set your amp gain appropriately so you dont over power the sub. Read up on how to set your gain with a multimeter.