Affordable accommodation upon my research in Sydney are mostly found in Kings Cross. Good prices from airbnb are in Darlinghurst. But, accessible location would be in main thorough fare of George Street which is near the Light Railways in Haymarket, Townhall station and Wynyard station.
Pensione Hotel Sydney, Haymarket
Location: 631635 George Street, Haymarket, NSW, 2000 Australia
Price: Discounted - Upon comparing the official website, agoda and expedia, the lowest price for 1 shoebox room for 7 nights (P25,567.53) is in expedia (with 10k php hot deal discount).
Check-in: Quick and easy - Check-in time starts at 3pm. But if they found the room available they can let you in upon arrival. They would also need 100.00 aud as a deposit, just surrender the receipt upon check-out.
For early travelers, they have guest lounge where you can take a rest and freshen-up before you start the day.