How to Create an Einstein Graphic Tee Without Spending $30?

[MPKU]

So, I'm a big fan of this t-shirt...

http://www.redbubble.com/people/chuckirina/works/10042759-live-for-today?body_color=black&p=t-shirt&print_location=front&ref=shop_grid&style=mens

However, I don't feel anyone should have to pay $30+ (after shipping) for a t-shirt. I've tried making pretty much the same image on one of these custom t-shirt sites, however whenever I add the image, the t-shirt color on the websites is a different shade of black from the one I use. Therefore, my shirt looks has a square outline of where the image was added. I've tried matching the colors, however I did not prevail. Can anyone with better skills at photo editing point me in the right direction / how to get this for less money.. Thanks

 

[robphy]

Can you make the black color "transparent", then save in a format (like .png) that supports transparency?
Software like Photoshop or GIMP or ImageMagick can do this... there are probably online tools that can also do this.

 

[BCHC]

That exact same design is also on Society6 and the base price is lower there.