Just recently, my boyfriend and I also went to Miami for a couple of days' vacation. We also immediately started looking for inexpensive hotels but didn't find anything special. We started asking people we knew where we could find cheap hotels for a couple of days.
Check the best hotel deals reddit?, you can find a lot of useful information there on how to find the best fit for you. That's how my boyfriend and I found a hotel for ourselves and a pretty budget one.