Some people just want to shoot stuff and not have to worry about petty things such as power management or quirks/shortcomings, they don't care for the vanilla challenges. Some just see it as a creative outlet to make a badass sub. Good as a learning experience too. Obviously, they set the price low so that they can afford their masterpiece early on in the campaign.

The majority of my sub creations on the Workshop are pretty simple really, and hopefully the price reflects this.

I see
I prefer to get badass ships in late game at a higher price lol