Does anyone know if it's possible to copyright a logo from a company that is no longer in business? There is a local company that has been out of business for decades. I was looking at getting some t-shirts made up for people that might be interested in them, but someone mentioned that a t-shirt place may not produce them because the logo has a copyright on it (or probably a Trade Mark I guess). If I was unable to talk the t-shirt place into making them, the idea struck me to try to gain the rights to the logo myself.

Does anyone know if something like this is possible? Would it be mega expensive because I'd have to hire a lawyer or is something like this impossible to gain rights to because it's considered public domain?

Short answer: It's probably not copyright you're talking about here, but either a trademark or service mark (trademark used to advertise goods, service mark used to advertise a service). Either can be lost through disuse or expire, so if the company's been out of business and not using it, it may be yours.

Long answer: I'm not a lawyer, and the advice of a competent IP attorney would certainly help you there, but you may want to read up on the trademark application process (like here, or here) and maybe try the search referenced in the first link to see if it's still even registered. If not, go for it.

There was a deal where some guy tried to trademark the PRR Keystone 30ish years after said railroad merged itself out of existance, so he could collect royalties from model makers.

You probably won't win many friends if you try to enforce it, and someone who can document prior usage may well try to sue you.