I needed to print some documents this week.  The advice in the forum was a good start but seemed out-of-date.  And the suggestions to buy a printer were not at all helpful for even long-term visitors.

So this is what I found with a quick search:

Buddy Internet...

...opposite Kad Suan Kaew

...B&W 5 baht per page

Eve Laser Print...

...basement level of Kad Suan Kaew (due to renovation now located in the back near the parking lot entrance)

...B&W 2 baht per page

...as low as 1 baht per page depending on volume and number of pictures that take more ink - I had 23 pages printed for 28 baht

 

I think 1 baht a page is as low as you're going to get for simple copying here unless it's a very high volume print job.  Then I'd recommend BluePrint Design, behind D'Vieng Condo, not far from Kad Suan Kaew.  Incidentally, K. Kornchai at Blueprint design does very nice design work for thinks like posters, banners and tickets, too and speaks very good English and German.

 

http://www.blueprint-graphicdesign.com/