the problem is that most tv series and some movies do NOT have enough designs for a full fledged strategy game. if you look at sins you have approximately 15 ships per side and about as many structures. now, if you mod facions like you listed above, what options do you have?
humans:
F 301 (rebuilt goa'uld glider)
F 302 (combined airplane - goa'uld glider)
X 303 (prometheus class capital ship)
F 304 ? (deadalus class capital ships
and thats about it for humans, save for scavanged ships of other races. so, bottom line is that it will be very hard to build a mod with sufficient ship variety based solely on the series. if a modder included some own designs that meld with the existing style, I'd be happy to give it a try, I just wanted to bring that to your attention.
for more info on stargate ships and techs, you can have a look at
WWW Link if you don't know it already.
btw. from the link: cost of development of hyperspace capable battleships 2 billion $

I wouldnt be surprised if development of the stealth bomber was more expensive. a nice series, but I never saw anything as detached from reality or plausibilty like that.