[alasyr]

My vote goes for building the first starting design and retrofiting up to final starbases.With balanced design (equal use of all resources) first design can be build in 1-3 turns (3 turns with SYI).Only the Last retrofit costs more than normaly building (of course it is the biggest step,2 times more, other retrofit are 20% cheaper) but 10-12 turns for building a RW kind a makes up for it.I've posted a spreadsheet that can help in planning base designs for retrofit.