As you would in life, you have to work to be able to afford items in buildings in Stardew Valley. While most you can afford after one or two seasons, some might be a little more expensive but absolutely worth it. Here are some items and buildings you should set aside gold for.
1. Furniture Catalogue
If you plan on making a lot of renovations and decor changes in your farmhouse, you might actually save more if you just buy the Furniture Catalogue from Robin's shop. You'll have access to almost all of the decorative items, and you can use it for the yellow couch exploit if you want *wink wink*.
2. Return Scepter
Unlike the Farm Totem that you could craft, buy, or find, the Return Scepter is not consumed after use, meaning that you can use the item as many times as you want. But, it will cost you 2,000,000 gold to buy it from Krobus in the sewers. It will be worth it especially if you do Mr. Qi's Skull Cavern challenge.
3. Horse Flute
There is more than one currency in the game. Aside from gold (G), you'll also earn Qi gems and Golden Walnuts. Qi gems are a lot harder to get, but they can be used to purchase the coolest items such as the Horse Flute for 50 gems. The flute will allow you to call your horse anywhere outside, which will be convenient in more ways than one.
4. Pierre's Missing Stocklist
Pierre, no matter how annoying he can be to some fans, is the main source of seeds in the game. The problem is, he only sells seeds that are appropriate for the current season. You can purchase his stock list from Mr. Qi on Ginger Island to unlock all his items for every season.
This can be very useful especially if you start working on your farm on Ginger Island. In case you don't know, the island has a tropical climate, which means that you can plant whatever seed you want all year long. You can buy it for 50 Qi gems.
5. Junimo Hut
If you like your farm automated, you don't have to stop with auto-grabbers, auto-petters, and sprinklers. If you build a Junimo Hut, they will harvest the surrounding crops for you once they are fully grown within a 17 x 17 tile area.
You can get them from the Wizard once you finish the quest where you retrieve his magic ink from the witch, which is also his ex-wife. It only costs 20,000g, but you'll also need 200 stones, nine Starfruits, and 100 fibers.
6. Island Obelisk
The Wizard also offers various obelisks that could warp you to key locations like the beach and the mountains. The Island Obelisk can transport you to Ginger Island quickly. Out of all the locations, the tropical island is the most time-consuming one to reach.
Once you build the Farm Obelisk on your Ginger Island farm, you can go back and forth as much as you like. It won't be cheap though. It'll cost you 1,000,000g, 10 Iridium Bars, 10 Dragon Teeth, and 10 Bananas.