It depends on too many factors. It just comes down to what people are willing to pay. Start higher and you'll find out if it's too expensive. DA doesn't mean much, so I can't judge. The power of a website really comes down to its backlinks. Although ahrefs DR is a great indicator. You won't see a low DR with good backlinks or a higher DR like 20+ that doesn't have good backlinks. And 30+ DR will always have good backlinks.