Some thoughts of mine on this, if that's alright with you fellas?
Ultra low cost drones should take into account the number of docking blocks they will need as well. Being 17 blocks tall uses about 5 blocks. That's more in the heavy drone size range than the expendable low cost range. Try shrinking it down to about a 9x9 that'd be much cheaper and you could fit vastly more of them. Which seems to be what you're planning to do.
Also on ultra low cost, numbers > damage. You could (I have so I know this works) actually use just the basic cannons and up your number of drones by 2x-3x to get roughly the same results. I use OD on weapons with large cool-downs for a solid burst at range, usually lasers/small missiles. Cannons with OD.... meh I'd go for it if you're talking about a shield breaker but otherwise nah. Just get more cannons and save the expense of those darned effect computers(which is like buying 20 guns a piece anyways).
So yeah ultra low cost means small in size too. If you reduce the wings down and chop a single layer of the center core off the top and bottom.
___
--/------\----cut this layer out <--
-/---------\
/------------\
|-------------|
\------------/
-\---------/
--\------/----and cut this layer too <--
You'll end up with this...
-- _____
-/---------\
/------------\
|-------------|
\------------/
-\______/
Which is still very Tie-esque and saves you like 18-ish blocks that could be spent elsewhere.
I'd also recommend reducing the bomber's size a bit, but it's more gorgeous than the Tie
. So it's problems are excused.