If thats your budget then the Alpine upgrade will come just under that fitted. Best thing to do is ask a few dealers and try and get their best price. Or look in the classifieds. If you recode then i think rear PDC gongs disappear or become very low.
I have heard the Alpine upgrade before. It is definately an improvement and i was tempted by it. But aftermarket sounds a lot better quality wise, especially with an ms-8. So its up to you. If you want a decent easy upgrade that once installed you can forget about then go for the Alpine upgrade. But if you want to build your own custom system with hand picked equipment, and are prepared to wait, then go aftermarket.
2008 E92 335D SE
2010 E90 320D SE
1994 E36 318I SE
1996 E36 316I SE