I've suffered from this for about 2 and a half years and eventually paid a visit to a chiropodist. He told me that I had excessive pronation which leads to plantar fasciitis. In my case I don't have heel spurs, it's just my arches that get sooo sore, hobbling around first thing in the morning!
He suggested that I purchase some otc orthotics to see if they would make a difference - and they did! The ones I purchased are Vasyli - they're the 3/4 length premoulded ones. They cost approx €40 - which translates to approx $55. I purchased another 2 pairs and rotate wearing them - they wash out fairly well as it's only the covering that's fabric.
Once the problem had cleared up I stopped wearing them and didn't use them for 6 months or so which in retrospect was too long. I'm back to wearing them again as I don't want my feet to end up as sore as they did the last time.
I wear mine in runners, work shoes (1.5 to 2 inch heels) with no difficulty - I'm a normal-width US size 10.5 and they fit fine.