How to unlock the Calico Desert (Stardew Valley)

The Calico Desert is a big area in Stardew Valley with a shop, a fishing spot, a casino, the Desert Mine, and a few other things. To get there you simply need to buy a bus ticket from the bus stop after having fixed the bus. Each ticket cost 500g, so you do need to pay every time you want to go to the desert. You can travel from 10:00 to 16:00, but you are free to return back to Stardew Valley at any point. The return ticket is free, and the bus will always wait for you, so there's no need to worry about not making it back.

How to fix the bus and unlock the Calico Desert

The bus is fixed once you have completed one of the following things:

1) You have completed the Vault Bundle at the Community Center. This is the only bundle that requires gold instead of certain items, and there are 4 different bundles you can buy:
2,500g bundle.
5,000g bundle.
10,000g bundle.
25,000g bundle.
So in total it will cost you 42,500g to complete the Vault Bundle and fix the bus from the Community Center.

2) You have bought the Bus Repair for 40,000g from the Joja Community Development Form. This is the option for players who sided with Joja instead of the community. Simply go to JojaMart and pay 40,000g to fix it, and it will be functioning the next day.