Depends how often you think you'll camp and for how long at a time. If you're thinking only once or twice a year and at least a couple of nights I'd just get a cheaper dome style ... probably a coleman (eg. lakeside 7). You could get a nice one well under $650.
If you're doing a few more trips then consider a blackwolf - maybe even a turbo style one (quick and simple). We can the 300 plus lite and it is big enough for 5 and would come in around $650 on special.
I don't know anything about the Diamantina tents.
Don't get something that's excessively big as the painful setup will put you off camping!