Just went to the kiosk in our mall here in Houston and they wanted $55 to put my name on the back of a polo (embroidered). It was first and second, so that was for 2 words. I wouldn't get my hopes up too high on the mall idea.
I ended up using a arts-and-crafts person recommended to me that had an embroidery machine. She charged me $15. But that is dependent on you knowing someone with a machine.
Another option is to use vinyl letters or iron-on letters. Looked at that also and it was about $5-10 for a pack of 2" iron-on letters. Depending on the number of letters that could be a good option.
I have not heard the greatest of responses on using the printer-based iron on systems.
Getting screenprinting is also an option depending on the number of colors and the initial cost for the screen.
All this is to show that the $70-100 from the big name sublimation companies isn't too bad. You can go cheap with a cheap shirt and cheap lettering, but you might get a cheap outcome also.