I had also thought of just buying glass polishing kit, but first I called around just to see what a glass shop would charge. Every and I mean every shop said they don't polish glass for one simple reason, you end up with a wavy appearance. Much like looking through waves of heat. Unless you can apply perfect uniform pressure through out the whole process, you're going to get this wavy appearance. I had asked for a price quote to replace my windshield and I was told $275 installed.
Now of course I took this advice with a grain of salt, after all they are in the business of selling new windshields. I may try to polish it anyways, hell I can't make my field of vision any worse.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member