i may be a kid, but since the GTVA rhules the entire known galaxy, why cant they just TAKE the resources? why cant they just tell the independent shipyards "hey you, yur workin fer us now! GET WORKIN ON MORE COLLIES!!!!!!!!! OOO-RAH!!!!!!!!!!" 
Because workers would say:
"Hey you, we're on strike until we can have unions, free health care, free deuterium for our civilian ships, a pay rise every week ... and... um...
oh, and you can't bomb us, because you won't have the shipyard! HA!"
Now a little more seriously, and back to the topic:
I think there should be no more Collossi, here's why:
A fleet of corvettes with a front mounted Mjolnir gun would be useful for hunting bigger ships down. Such a Cv could easily outmaneuver an SJ Sathanas and could be used in groups, with all ships behind the Jug (all it takes is a Pegasus to find out where the Cv's need to warp out), so the Big 'C' loses one job.
The Corvettes would be useless against anything with good 360* coverage of main guns (unless it's a cruiser that gets killed with one or two Mjolnir shots) so a couple battleships, bigger than a destroyer, but much smaller than a juggernaught, say 3-4km long would need to be built. Their role could be hunting down destroyers, being flagships, or even blockades. Hunting down destroyers and corvettes was what the Big 'C' did best, but you don't really need a 5+ km ship to do that.
The battleship would need LRMjolnirs (Long Range meaning some 10 km) mounted on rotating turrets to need only one beam cannon to cover both port/starboard, thus lowering main weapons cost (and with 10 such turrets we have the broadside of a Collossus). Less weapons = smaller size, and again smaller total cost. Smaller size = smaller engines required ... etc... and with a ship 4 km long, you could still put lots of armor, giving it similar HP's to the Collossus (judging by textures some parts of Big 'C' didn't have heavy external armor because the frame construction was visible) and some 50 turrets. That makes the Big 'C' WAY overpriced, with it's huge amount of turrets an advantage in only a few situations.
To hunt down jugs with good all around coverage of main guns, 2 GTVBB's with support from the Mjolnir Cv's forming a battle line could broadside whatever may be used against the GTVA much more effectively than a Big 'C'.
Since the BB's will be filled with reactors rather than fighterbays, we also need a carrier, more/less the size of the battleship. That way our beam carrying platforms (both the BB's and Cv's) could have almost endless waves of fighter and bomber support. So the last great advantage a Collossus has - it's hangar - can also be delivered to the battlefield better and cheaper.
Would a fleet of a Carrier + 2 Battleships + 10-15 Corvettes be cheaper than a single Collossus? Probably not, but it could be scattered to secure whole systems, and hunt down multiple Sathani simultaneously, things even 2 Collossi can't do.