i stepped on my neighbor’s prescription sunglasses that she laid in her driveway-the frames were broken ; they were purchased in 2005 for $99

To begin with, I'm not sure you're liable.  This isn't a case of what lawyers call strict liability, which in simple english, for this case, means you aren't liable just because it was your foot.  You would only be found liable, in court, if your neighbor could convince the judge that you were careless.

A court can find that parties share the blame, that both were careless in a way that helped cause the accident.  What were the sunglasses doing on the driveway in the first place?  And the court can divide the blame by whatever percentage it sees from the facts.  If your neighbor is found to be 50 % or more at fault, she can't recover at all, from what my research suggests.  If she's less than 50% negligent, but more than zero, what she gets is reduced by that percentage.

How much?  For the answer to that, and for how this law fits all of the facts of your case (including the details!), you'd need to talk to a lawyer in your area.  One place to find qualified attorneys is our website, http://attorneypages.com

Usually when a person breaks the belongings of another they will be responsible to replace said items. However in this case there appears to be a big discrepancy in price. Of course inflation will account for certain changes in the costs but what you need to do is ensure the replacements are of the same quality as those broken.

Furthermore although I feel you may not be completely liable being that an argument can be made for her contribution based on the glasses being on the ground it becomes your choice as to whether to legally pursue this matter.

You may be able to bring a small claims action for free or a small fee but will have to appear and of course there is no guarantee you win. If you want to simply get more advice you might want to call a local attorney and run the situation by them, get their opinion and decide how to proceed at that point