It was for me. I couldn't turn the hand crank one so I sold it to a friend.
Yes the dies are expensive so I got some from family for Christmas gifts etc. I bought the strip ones like 2 1/2 etc. I also have some of the circle ones 1/2 sq etc.
I shopped on Amazon and other places and compared prices. My actual Go! Big was purchased on Amazon by Elanor Burns offered it for around $350 and I think shipping was free.
The reason for the various mats is to fit each die. You have to have enough to cover the sharp blades in the dies so it doesn't ruin the roller or too much might hinder it going through.
I heard Accuquilt has specials around Christmas time, but I found mine on sale way before.
Good luck and if I can help you further please send me a private email if you like.