Re: space yards
 

Plus the maintenance costs. And in some cases ship limits come in to play. If you are modding however you can eliminate the maintenance by making base yards that only fit on one size base, using mounts or an oversized base and base yard to match, and then giving that hull reduced or eliminated maintenance. You can also increase the maximum ships to compensate for the added base yards.

Re: space yards
 

In CW's invasion game, the SYs and maintenance are close to stock.

I've got 330 BSYs, pumping like mad to spend well over a million minerals a turn, supported by a modest empire, resource conversion and trade income slightly more than what I produce locally.

The trick is to take a large racial maintenance reduction.