This is random and stuff, but unless the economics of your fantasy world are really narratively relevant, just base the money off of whatever currency is used where you live. You probably have a pretty decent sense for how much things cost, and while that may not map perfectly to your story's world, you will probably deal with it more consistently than if you have a made-up money system.
Again, if the money is important to the story, then more power to you. You also don't have to follow the advice of some rando on the internet anyway. But if you don't want the money thing to feel like an issue, just think of it as dollars, pounds, yen, euros, pesos, etc. and give the currency your whimsical fantasy/sci-fi term for texture. Don't let that hang up the telling of your story.
