Out of curiosity, I looked up up the Sew Steady Grid Glider to see what it is. Before you purchase something like that, you may want to try out some of the very inexpensive things you can do yourself.
Deb Tucker has a good
video showing how you can use painter's tape to make a 1/4" seam guide for accurate seams. I set up something similar on my machine using post-it notes, taped down. I really like that it it is a raised guide that I keep the edge of the fabric against, rather than a line to watch. Some people use things like mole foam (a blister protection product) to make a guide.
The Grid Glider also has lines to help with sewing seams 1/4" from a diagonal. You could put a piece of painter's tape on your machine bed and mark those lines yourself.
The Sew Steady Grid Glider looks snazzier than home-made guides, which will appeal to some people.