Lots of folks are curious about stitch guides. What are they exactly? What do they cost? Where do you find one for that canvas you want to stitch? The answer to the last question is easy--you browse here!
But the first two questions don't have easy answers because guides vary widely in costs (from free to hundreds of dollars for a custom piece) and layout. To help answer this question, I have collected guides for you to look at or read about in the links below. First up, a review of Amy Bunger's stitch guides and a brief explanation on why you can't buy them without buying the canvas and/or thread kit with the guide.
http://chstitchguides.blogspot.com/2011/01/amy-bungers-stitch-guides-review.html
Here is a review I did of one of Beverly Churchfield's stitch guides.
http://chstitchguides.blogspot.com/2011/02/review-vintage-pears-stitch-guide.html
Here is a review I did of one of Robin King's stitch guides.
http://chstitchguides.blogspot.com/2011/08/reviewing-robin-kings-stitch-guides.html
Needlepoint.com also did a review of some of Robin's guides.
http://chstitchguides.blogspot.com/2011/11/robin-kings-creepy-creatures-set-guides.html
CBK has some free stitch guides on their website for some of their many canvases. These vary in style and layout because they are from a lot of different stitch guide writers.
http://www.cbkneedlepoint.com/Stitch_Guides.html
Palma Seljan has also created quite a few free stitch guides. Some have been posted here and some are available at Needlepoint Nation group on Facebook in the Files section.
https://www.facebook.com/groups/NeedlepointNation/