Hmmm.... wish I could help you out... but I agree with fannaticsydney... If you do decide change the straps, the straps would be a lot lighter than the rest of the leather trimmings...
i think the replacement cost is around AU $150 depends on which bag and strap?
i had my nolita handle replaced as it was scratched badly after a year (dont ask me why, my ring!!!!!) in singapore, and it cost around SG $168 something and it took 30-60 days depends on the local craftmanship which lv depends on or using