$300 a year is nothing compared to colocating your own server, or even getting a business-grade network connection.
If you can get away with hosting on your own computer on a residential connection, that's great for you, but it's a totally different product from what AWS/GCP/colocation offer.
By the way, reserved instance pricing on AWS and GCP starts around $20/year. But if you know how to use S3/GS and Dynamo/Datastore, you don't even have to use an instance.