I agree with Mar, because also in auction even if people do bid you risk the chance of not earning what you expected.
So if you think it's something worth auctioning than go for it.
But if you think you'd get a more reasonable amount for your work in premade do that.
Like Mar said too though auctions are pretty slow nowadays, but don't want that to discourage you.
In the end it's really what you would feel most comfortable with. If you choose to try auction and it doesn't sell you can throw it out there for premade, and if it sells for less than you were hoping then maybe premade is better. But I don't think most people are throwing big bucks toward auctions like they used to.