AI picked this up at Michaels today, with a 50% off coupon I paid $5.
I still struggle with piping letters, although I will more likely use this as a stamp than as a lettering guide. Still a great find for the price though.
Wilton have one of these also that I bought a few years ago (at a lot more than the $5 this one was on offer for!). I think you are right about using it to impress letters into fondant with it instead of using it as a piping guide - so hard to pipe letters so rigidly straight and perfect!
Best advice I ever got for piping was to move your whole arm when piping and not just your hand- try it!
AThe Wilton one was $22, I thought about getting it a few times but never did. Glad I waited now!