I have a cocker/lab mix. But she does have the cocker floppy ears. She was getting ear infections constantly too! And yes those vet bills add up. She was actually diagnosed with chronic ear infections. We were told that more than likely they would just keep reoccurring regardless of what we do. It is just part of the breed and just continue with prescriptions.
But what I did find that helped our dog was taking her to the groomers about every 8 weeks. I told our groomer that she had an ear infection so to watch that ear so it didn't get any more water in it. After I mentioned the ear infections she started to clean her ears really well. She would also shave the inside of her ears as well as giving them some sort of vinegar cleanse or something. Not really totally sure what all she does but I know that her ear infections have dramatically cleared up and now only gets them about once a year or so.