Tokyo's reputation for expense is exaggerated. Convenience store meals (7-Eleven, Lawson, FamilyMart) are excellent and cost $3-6. A bowl of ramen runs $8-12. Lunch sets at proper restaurants cost $10-15 — significantly cheaper than dinner. The Suica IC card makes transit seamless at $1.5-2.5 per ride.
Budget travelers can manage on $60-80/day including a capsule hotel ($25-40) or guesthouse. Mid-range travelers spending $150-200/day can stay in business hotels, eat at diverse restaurants, and visit major attractions. The 72-hour Tokyo Subway Pass ($13) is excellent value for heavy transit users.