Really cute! Cute enough to get more than $4 for! I know it's hard for us to put a realistic value on our time, but even at $12/hour (cheap), you'd have to be making one in 20 minutes, start to finish and that doesn't take into consideration the cost of your materials. You should be compensated for your materials, time and your quality work. Charging $9 or $11 might be something you can live with and the odd number will make them feel like you actually calculated your costs.