I've found that replacement insoles are worth the expense only if they provide something that you really need and the shoe doesn't already have. I'll give you an example - I wear motion control shoes, which are great on support but tend to be rather thin on cushioning. So I replace the standard issue insoles with Sorbothane insoles in order to get some more impact cushioning. That works for me, but it's somewhat of a unique case.
"...I've learned that you shouldn't compare yourself to the best others can do, but to the best you can do....I've learned that you can keep going long after you think you can't..." --- author unknown
2009 highlights...
• @ 10K: Fiesta Days Run, La Canada, CA, May 2009, 50:53
• @ 5K: Downtown Anaheim 5K, Anaheim, CA, June 2009, 24:45
• Long Beach Marathon, Long Beach, CA, October 2009, 4:43:10
• Post-marathon: Calabasas Classic 5K, Calabasas, CA, November 2009, 25:14