The only cheapp stuff in South Beach is hostels. If you hate the idea of hostels, you can check if they have private rooms.
Twizi.com list four hostels in South Beach for less than 25 dollars! Goto their Miami page by following the link below.
Miami South Beach info....
Each of these hostels are in South Beach (the art deco district) within two blocks of the beach. These Miami hostels are listed by price.
The South Beach Hostel
$16.00 and up - The South Beach Hostel is the newest of the backpacker hostels in Miami Beach, Florida. We offer hostel dorm beds as well as private rooms at the lowest prices of the Miami youth hostels. We also have some of the best facilities for backpackers and budget travelers in Miami. All of our hostel prices include free Internet, free breakfast, and free long-distance phone calls to anywhere in the USA! The South Beach Hostel is the best value of the hostels in South Beach Miami. All of our prices include free breakfast, free Internet access, and free long-distance phone calls to anywhere in the USA (you can also use our phones to make international phone calls with a phone card). Our Miami Hostel is less than 2 blocks from the best section of Miami Beach. We have a full kitchen and a large bar with nightly drink specials. We have three lounges, with pool tables and cable TV. We are just two blocks from the clubs, restaurants and nightlife that South Beach, Miami is famous for. The South Beach Hostel is the most fun of the hostels in South Beach. Hostel info / Book online
Miami Beach International Travelers Hostel
$16.00 and up - The Miami Beach International Travelers Hostel is located on Miami Beach, in the heart of the Art Deco district also known as Sobe. The whimsical motifs of the low rise structures along with the excellent beach weather and local attractions make South Beach a diverse international playground. Their is a constant flow of people to Miami from all over the world and everyone ends up here in SoBe. Beds start at $16.00 and Rooms start at $36.00. When visiting Miami and world-famous South Beach, come stay with us, right in the middle of all the action, and the historic Art Deco District. Go clubbing and dancing till 5am! We're surrounded by the best nightlife hotspots like Level, Opium Garden , Crobar and the Clevelander. 9th Street beach is just steps from our front doors, play volleyball, swim in crystal blue water, rollerblade the strip or sip a cool drink from one of the Ocean Drive cafes. Great restaurants and good prices are close by too! Our full service, family owned hostel is the best value on the beach: 28 clean, comfortable rooms and definitely the best location. Don't be fooled by imitators. We are the closet hostel to the beach. Hostel info / Book online
The Clay Hostel
$21.00 and up - The Lonely Planet guidebook calls us "the most beautiful hostel in America".
Another guidebook, "Hostels USA" awarded us its top billing of four stars, naming us one of the best big city hostels. We believe that's because of our great room rates, terrific Mediterranean ambiance, and location in the heart of South Beach. Our Miami hostel has both male and female dorm rooms with four to six beds and all include a private bathroom on suite, air conditioning, a ceiling fan and a refrigerator. Sheets and towels are available from the front desk just with a deposit. We are affiliated with Hostelling International, the largest worldwide hostel network with over 5000 hostels worldwide. Dormitory accommodations start at a very good price per night. Members of Hostelling International get a discount, and if you want to join, memberships are sold at our front desk. We offer the members rate for groups over 4. Hostel info / Book online
The Tropics hostel and Hostel
$22.00 and up - Sizzling Nightlife, parties till the morning comes, gorgeous beaches - this is Miami Beach. And all that action is going on in South Beach. So if you come to Miami - stay in South Beach at the Tropics hostel and Hostel. Because our Miami hostel is right in the center of everything, has clean, newly renovated rooms and an Olympic size swimming pool. The Art-Deco- and Nightlife District and the beach are just there, all in walking distance. And our Miami hostel rates are very competitive. Dormitories are a unique form of accommodation. They are unique in that facilities are shared with other guests. Our dormitory is furnished with 4-8 bunk beds per room. The bathrooms are attached to the rooms and shared only with the other people that stay in your room.
For security reasons we do require a valid passport from everybody who wants to stay in our dormitory. Hostel info / Book online