The following is a response from Tim OBrien, author of the Pirates & Privateers supplements
There are probably several reasons why ships cost what they do. The YT-1300 is supposed to be a very common, highly adaptable ship, loose-engineered, brick-tough repairable, and classic — plus, they don’t make them anymore. Also, a used YT-1300 almost certainly has a few extras not mentionable in legal company, and is so dirt common that nobody blinks to see one. All these probably helps keep the price up.
Other ships may suffer from lack of available parts, as mentioned, poor durability, limited production runs (resulting in few replacement parts), strange breakdown problems (it explodes if it gets rear-ended), species-specific control systems, and Maker knows what other difficulties. So, the YT-1300 tops them all in length of production run and retained value. It’s sturdy and reliable.
Another point — the value of a cargo ship isn’t based strictly on simple functionality. If your ship doesn’t have adequete hull armor and weapons, it’s a liability. The Corona is an easier target than almost any YT-1300.
On top of which, those are local market prices. Some of these ships are for sale in local galactic markets where prices may vary.
Those are the internal gobbledegook reasons/rationalizations. Now for the external ones.
When I was researching and writing this chapter, I knew things were wonky, but there’s nothing to be done about it. These ships were compiled from heaps of sources (just look in the index). Very few writers bothered to be consistent with other ships. Everybody seems to have written up something to top the basic YT-1300. One-upsmanship ran riot. I actually downgraded a lot of those ships without seriously lowering their prices. The current crop of West-Enders are trying to be internally consistent, but former folks don’t seem to have had any systemic view.