Katia has very good advice!!! I cannot wear the cheap flip-flops for many of the reasons mentioned, however, I do have some aerosoles brand, some addidas, and some jelly type ones I bought at Coldwater Creek several years ago that I wear all the time!!!
I will also say that I only wear my flip-flops at home and when I go to the store, etc. I do not feel they are appropriate or professionally acceptable. For instance, I would not wear them to school (I teach K) except on specially designated days like...beach day or (yes) flip-flop day. I do wear sandals to school but never the flip-flop style.