Tattoo prices depend on a number of factors.
The quality of the tattooist is generally the most contributing factor as the better the tattooist, the more it will be. Whilst it might be tempting to spend less in order to save money, this is something you will have for the rest of your life so it's best to invest a little.
Also, the detail of the design and the size of the tattoo will contribute to the price.
I got a tattoo on my thigh spanning halfway around the leg, which cost me £150.