Your labels can be printed on printable fabric - I get mine from here. I only buy seconds and they have never been a problem. I can email you the template I use if you like, I fit six labels to a sheet.
You can also use a Michron Pigma pen to hand write your labels. These are available in most quilt stores. Hand writing not neat enough? Try printing out the wording on a plain sheet of paper, taping it to a window and tracing over it.
I am not an expert in other pens and you can't just trust a permanent marker or a laundry marker as not all of them are as permanent as you would imagine. If you want to use something other than a pigma pen please write on a test piece first and run it through the wash with your laundry a few times just to be safe.
A few people have told me that they print their own labels by ironing fabric onto freezer paper and putting it through their printer. As far as I know this does not work as the fabric that is sold to go through the printer is treated to make the printing colour fast.... if your fabric has not been treated, again you should do a test and wash it to see how long the printing lasts.