T-shirt Design Service

I was researching on how much to charge for a t-shirt design work. I really don't have any idea how much it is. Based on my research, it costs one hundred to more than a thousand pesos. If I follow this rate, I guess it would be too expensive.

So I was thinking to just base it on the "Typing job" rate. Typing job costs P25 per hour (with print per page). That makes the T-shirt design P30 per hour (without print), would that be reasonable for your guys?

Comments and suggestions are welcome. =)