I think you might find that 600k will go a bit farther here than you expect. Unless you're looking for a "custom home" on your property, or you wish to live in an exclusive neighborhood then you should have no problem at all finding something with acreage for that kind of money, with plenty to spare. Average single family homes can be had for ~200k, and exclusive communities less than 500k.
Jacksonville is a very large city - the largest county landwise in the nation. What is important to you? Proximity to work, beach, school, shopping - or perhaps a little away from the madness?
Scott