How much does it cost to play by yourself? Will 5000-8000 be enough for 7 days?

It depends on where you go, what you eat and what standard you live. The biggest expenses for going out to play are travel expenses and accommodation expenses. If you want to go far away, the fare will be more. There is also the choice of transportation, and the cost is different. Accommodation is the same, youth travel is cheap, and hotels are definitely expensive.