Custom orthotics can work well, if they're the right ones, but one of the things that affects how well they work is your shoes themselves. How worn are they, how much slant has been worn into the sole, and how much has the interior support pad been altered by your foot? The custom orthotics can't take these things into consideration. Start with a good quality over the counter model. "Superfeet" is an excellent brand. When you put them in, take out the ones your shoes came with. (you wouldn't believe how many people don't) If you try 2 types, you'll get a good idea if they will work for you, and it won't be that expensive. If you have to go the custom route, (and sometimes it's the only way) make sure you put them in brand new shoes. Best of all get rid of it entirely by fixing the cause. If you've had severe ankle sprains, the resulting adaptive muscle shortening is probably to blame. Head to my website,
http://www.kaywarren.org. I have an entire page on plantar fasciitis, how it forms, and what you can do about it. Then ask me for the guide, "Healing Plantar Fasciitis Without Surgery". It's free, and I promise I'll never spam you or give your info to anyone else. I've been doing medical massage for 24 years. I went through this, I did nothing but orthotics and massage, I'm free of it, have been for 6 years now. It will help you too.