Finding it is not a requirement to finish the game. It just grants you access to the money making minigame that is covered in this question. I would suggest getting it as it is an easy source of rupees with little to lose and a lot to gain with relative ease.
Unless you are a very throurough in searching every spot there is in a map for anything, you probably wouldn't see this in your normal, go-for-the-objective adventuring. It's location is near a "hidden" chest and off the beaten path.
To reach it involves some ledge climbing and the help of a Timeshift Stone.
How to get it:
When you first enter Lanyru Desert (after exiting the mine), there will be a Timeshift Stone nearby. Hitting it will reveal some vines on a nearby wall that you may climb up.
There will be a ledge that you can climb up to to reach another cliff on the other side of the little gorge.
You will end up on a narrow land bridge where below you will see an isolated chest sittng by and the wheel at the end (in the corner). You can't miss it.