For excellent budget accommodation in Bangkok Yai, consider
Bang Luang House,
Toptel Thaphra,
Arun Old Town Hostel, and Season Place Hotel.
The 3-star Bang Luang House, with a fantastic 9.0 rating, offers complimentary breakfast, including local options, and free toiletries, along with free WiFi. It is incredibly convenient for visiting the Khlong Bang Luang Floating Market, being only 0.1 km away.
Another good option is the 3-star Toptel Thaphra, rated 7.4. This hotel provides free WiFi, a complimentary stocked minibar, and free self-parking. It is located 0.8 km from the Khlong Bang Luang Floating Market.
Arun Old Town Hostel, which boasts a 9.0 rating, offers a 24-hour airport shuttle, free toiletries, and free WiFi. It is well-situated for exploring several attractions, including Wat Arun (0.7 km away) and Wat Rajapradit (1.6 km away).
Lastly, the 3-star Season Place Hotel, rated 8.0, features free WiFi, free self-parking, and rooms with balconies or patios. It also benefits from being in a shopping district and is 1.5 km from Khlong Bang Luang Floating Market.