So what is the correct way to spell it, bandanna or bandana?

According to the Marriam-Webster dictionary site bandanna is correct:

bandanna

Main Entry: ban·dan·na (bandanna)
Variant(s): ban·dana (bandana)
Function: noun
Date: 1741
a large often colorfully patterned handkerchief

But if you do a search on Google for “bandanna” it will suggest that you switch to “bandana” showing that “bandana” seems to be the more popular version on the web.

If you don’t care how it is spelled and just want it custom printed with your logo, message, map or whatever, our custom printed bandanna / bandana page is great place to start looking.

Most of our bandanas include a 1 color screen printing and all setup charges in the price.

We now also offer pigment printed bandanas in quantities as low as 2500 pieces. Pigment Printing or Roller Printing produces a top quality product and allows for a larger all over imprint. Starting with rolls of white cloth we print up to six colors including the background color with pigment dyes. The printed cloth is then cut and sewn into the finished product which is colorfast and soft-textured.

Pigment Printed bandanas work great as maps for parks, trails, cities, colleges and schools etc.