I think 10$ for an obvious weekend hack is quite a lot.
But people will pay $300 for a lawyer writing a letter which says, attached to the letter, "This took forty eight minutes to write."
And this is why you should never, never take pricing advice on HN.
[Edit: My conclusion here was excessively strong. Working on a blog post now, because I feel the need to vent a little about this. $10 is not a lot of money. Customers do not pay for how much you appeared to have worked. Argh.]
Also, lawyers are overpriced, but that's another story.