the biggest reason that i dont think that this is the right option for you is that those 750.1's usually come in at about 900-950 real watts RMS depending on the birthsheet, and the W3 is only good for about 500. that is way into the red zone, sure it is possible to run an amp that powerful without problems, but it is easily enough power to toast that sub in an instant if your not super careful about the levels
I can get a sub twice as strong for less than that.
which would be a much better idea because of the above
The only problem I have I dont know how to build a box. That's the only reason i'm looking at this Subwoofer Enclosure.
boxes are easy to build if you know how to run some power tools, or you can go to any shop and get quoted for having them build one for you, a lot of times you can talk to the guys and tell them what you would like to stay under (cash talks) and if its simple enough can be done for $100-$150, maybe less if you do all the math and have the plans all done for them.
You can get the 10W3v3 for about $160.00 so you have to ask yourself if the box is worth $100.00.
actually $100 bucks is not a bad price at all for a proper sized and tuned box, especially since its got a couple of nice features that makes it look better than a standard black cube
IMHO: for that price range, i would definitely shop around for a stronger sub for that amp, and either find some one that will build you a box or experiment around with building your own
edit:didn't see that last post, your pretty much have a 1kw amp, you really need a 1kw sub to go with it.