I can get you beach front land in RN for 60-70 reais per m2, but there isn't a great deal left at that price. Whilst I don't doubt that land in Aracaju will go up as you say, I will wager (in fact I already have by buying there) that land in RN also continues to rise pretty dramatically.I don't doubt that one bit. The difference between RN and SE is that, for the mostpart, the prices have already exploded in RN, that is not the case in SE, this is just the beginning. At this moment one can still buy large tracts of prime, beachfront land for approximately 60-70 reais per square meter. In my experience here in the northeast, particularly in Salvador and Aracaju, I honestly believe that in 2-3 years from now these same tracts of land will be selling for 120-200 reais per square meter.
I suppose it all comes down to your risk level, I have been offered loads of cheap beach front land over the years, some which I deeply regret not buying and some which I am glad I never touched as the area just never took off.