so the ciras would essentially allow for better mobility without plates then? If so I might look at a ciras replica. Any suggestions on a good one?
Do you want to go in that direction, or are you looking for a plate carrier? The CIRAS is a great vest, I wore one in Afghanistan, but it's a complete armor system not a plate carrier.
For a budget of 300, that allows for most anything.
Now, I'll ask again, are you looking for a plate carrier, real or airsoft knockoff, or do you not know what the hell you want?
And as for plates limiting mobility, I would recommend against using ballistic protective plates for airsoft unless you're trying to squeeze some training value out of shooting BB guns.