There is a lot to tell about inlay soles and heelcups and their relationship to heel spur and plantar fasciitis. Having a wrong stance of the foot is one of the main factors contributing to developing heelspur, and inlays can play a role in preventing this. Especially in the beginning stage of a heelspur it is possible to gain results with some pretty cheap heelcups, while for a little bit more you can have an inlay sole with even more support for the foot, sometimes designed specifically for heel spur. Let's discuss both:
Heelcups and heel cushions
You can find these at almost any decent shoe shop or drugstore, as well as on-line with orthopedic web shops. They usually are pretty cheap and can have their use against heelspur. Main reaon for this is that they raise the heel up. Raising the heel relieves a bit of tension in that plantar fascia and this may be enough to relive the heel pain. Also they may provide cushioning through either use of soft materials or by creating a nice cup for the heel to fit in. There are really a lot of heelcups around, so you may need to try some out to see which one fits best.
Also inlay soles can be found in a large variety, both in shops and on-line. They are usually slightly more expensive then heelcups, but still not too expensive. Usually they have the same effects as heelcups, but they add to that additional support for the whole footbed, with even added cushioning.
Remember that both heelcups and inlay soles deliver a standard solution, so they may not be fit for everybody. In case they don't treat the heel spur enough, please consult a doctor, or go to a podiatrist for some custom inlay soles.