So you had prior flight training? Did you take the part 61 exam? If you did, you passed, and you remember most of that, then I wouldn't waste time or money paying for an expensive online course. The weather, airspace and some of the regulation questions on the part 107 are the same or similar to the part 61. There were some things on the 107 that are very specific to sUAS, but most of them were common sense questions. I actually used two things to help me study for those and both were free. First I used the resources at 3dr to study and take practice exams. Just go to their website 3dr.com and scroll all the way to the bottom and look in RESOURCES for FAA Training. The other thing I used was an app from ASA Prepware. It was relatively cheap and I got it in the app store. I liked it the best because it not only let me take practice tests but it also let me study each individual module of the test material and gave me instant feedback when I got a question wrong, with an explanation of the answer. That way you aren't just studying to a test, you are actually studying the material. Having that feature encouraged me to do a search for more information on it rather than trying to remember the answers to the questions. I used that app right up till just before I went in to take my test. I sat in the parking lot and took two practice tests while I was waiting to go into the testing center. I will say though that not all the questions in either 3dr or Prepware are worded exactly the way they were on my 107 exam. There were also some questions that I had in my exam that I had never seen in any of the prep questions or any class.
I did actually sit in a 107 prep class. It was a one day class and it was free through my work. The instructor was very good, but in the end I have to say that I didn't learn anything in the class that I didn't already know from my own studying and using 3dr or Prepware.
Here is what I would suggest; Go to 3dr and take their practice test. If you score 85 or better, don't go out and pay for any class or software, just do some brush up yourself using free online resources, and then go take the exam. If you take the practice test and you score less than 70 then you probably need to either do some really intense self study or you might need a class whether online or in person.