How do developers consolidate multiple lots

[Dan Nad]

I'm looking at a house in a neighborhood with increasing multi-tenant development. It's a block that's perfect for knocking down all the houses and putting up an apartment or condo development. So my question is, how do developers consolidate all of these small lots before development? Do they make a blanket offer to all the homeowners or negotiate individually? How much of a premium do they usually pay for the land? Obviously the price has to be higher than land + structure in order to motivate sellers. 
Thanks