Flea collars (and sprays and baths) stopped working in our climate decades ago and would be a total waste of money, but I still see these products in some stores. Fleas developed resistance. Systemic spot treatments from the vet work okay. We use Advantage Multi, which is effective against a range of parasites, including heart worm, which is a huge problem in many parts of the country. It costs us around $12.50/month per pet, in addition to the vet's fee for annual testing because the dog has to be free of heart worms before the preventive is started. The one that includes the heartworm preventive is more expensive than the one without, except that we used to have to buy Heartguard or Interceptor in addition to the flea killer.
Once the fleas start to appear in your home, you can spend a ridiculous amount of money getting rid of them, so prevention is the only option. If your dog goes where other animals have been (including wild animals) he will inevitably bring home fleas.
We used to use Adam's Flea Off Mist years ago, and it's probably effective for a little while, in the same way that Off works for humans, but you'd have to keep using it frequently, and that's a lot of trouble and expense in the long run. The dog can't be sprayed on his face or below his tail, and you may see fleas congregating there.
It's best to ask your vet what would work where you are.