I would suggest looking into the action fleet line as well. It is clear Hasbro will not do 3 and 3/4 inch scale ships very often, and even then they are mostly repaints.
I have been following a few auctions recently, and a group of 10-12 ships in collector-loose condition average about $5.00 per ship- less than the price of a single figure. And the ones that you want multiples of (X-wings, ties, a-wings, etc) are among the cheapest.
I recently picked up a lot of the small playsets (transforming heads and planet scenes) from 1997 or so. Some were sealed, some had been opened and were missing a small figure or two, but they came to less than $5.00 apiece after shipping. Given the level of detail these things have, and how little space they take up to collect, I think it is a great line to get into.
My favorite part of the action fleet line is how well the snowspeeders look next to the Hasbro 3 3/4 inch AT-ATs. They are a great scale match for making dioramas-
Plus they can be hung from the ceilng easily to make flying scenes (Darth's Tie with two wingman and pursuing an X-wing is great conversation piece hanging above the television).