Airbag light on

The "airbag" light (on the dashboard) is on for some unknown reason. I did
not get into an accident or collision. I saw some people have the same
problem. I read some posts and it seems that it requires a good scanner to
get the code, and then decide what to do next.

I called the dealer near me and they asked for about $100 just for the code
reading (plus some diagnosis). I went to a local autoshop and they said they
did not do airbags since it was a safety issue.

I wonder if anyone can share how they deal with this issue. Do I have to go
to the dealer? Or could some better chain autoshops, e.g. firestone,  do
code readings about airbags? Thank you.