Yup, I sold it right after college for a few weeks, and then my conscience wouldn't let me keep doing it, since I was an art major and knew I was ripping people off. The company I worked for ended up on 60 Minutes (I didn't put them on my resume).
Lithographs and serigraphs are prints. Two different ways of making prints, but still prints. They are a great way to get beautiful works of art to decorate a home or office. They are not collectible art, even if signed and numbered with certificates of authenticity. Sorry.
I have a closet full of nice looking prints that my parents bought on cruise ships and thought I would like them, and someday sell for a profit. I used to hang them up when my parents came to visit.
You will see pieces just like yours online for asking prices of "$1,500-$2,500, like you said. The chances they will sell for anywhere close to that is very slim.
Again, sorry to be the bearer of bad news. Hey, I wish I could sell mine for enough to make a few house payments. Good luck.
“People say nothing is impossible, but I do nothing every day.” Winnie-the-Pooh