If FDev are prepared to do the work needed to implement carriers, it's in their own interests to get the maximum return on that effort. And hopefully that should mean bringing out a range of carriers with different sizes and prices.
There isn't any reason why a small personal carrier, capable of holding only a limited number of ships, should be a "megaship". And a carrier of this sort would only exist in the owner's instance and would disappear when he logs out, like any other ship. No extra server overheads at all.