That's a tough one, since the answer is very subjective. However, in my humble opinion I would suggest the following...
I'm not sure how familiar you are with Alpharetta. There is the west side of Alpharetta (west of GA400) which is more spread out/rural, like horse country. On that side the best school district is Milton HS, Northwestern Middle and either Summitt Hill or Crabapple Crossing Elementary.
On the east side of GA400 there are a number of options, all good, some possibly a bit better. Tied for the top for high schools are Northview and Johns Creek. Very, very close second would be Chattahoochee and Alpharetta. However, truly they are all very good. For middle school the top are Autrey Mill, River Trail. Then Webb Bridge and Taylor Road (although I don't believe you'll find any in your price range for Taylor Road...they are a lower price range). For elementary schools I'd say Dolvin, Barnwell, Wilson and Creek View.
Again, this is very subjective but if your score driven I think you'll find that the ones I listed will be at the top.
Please contact me directly if you have any more questions. I've been living in Alpharetta for over 11 years and absolutely love it here. My daughter went to Dolvin elementary and is now in Autrey Mill middle. My son is in Dolvin. We moved to this area specifically for the schools.
By the way...is Colts Neck any where near Long Valley? I'm about to start working with a family moving here from that area of NJ.
Hope to hear from you,