As has been mentioned, the problem is a lack of iconic small-medium ships in the films for imps. Rebels, on the other hand, is fairly popular and DOES have small ships in significant roles. So I would do an Aquitens and a Raider for imps. Not ships present in the films, but very recognizable to anyone paying attention to non-film material, and obviously hitting the imperial aesthetic for those that aren't. For the rebels, make it Phoenix Home and a CR-90. Similar matchup, good aesthetic, obviously rebel ships, and related design wise. Toss in some fighters and the actual essentials stuff and your good to go, at a much better price point.
I think most potential players are going to understand that the big ships like ISDs and Home One are simply not economical to include in a starter box.
Edited by Forgottenlore