ABS light comes on only sometimes on 1997 Saturn SW1

The dashboard "ABS" light comes on sometimes, but not most of the time. It seems to be about once in 10 driving sessions. It also seems like in damp, cold, wet weather it is more frequent. Does this look like a costly repair?

Asked by for the 1997 Saturn SW1
have abs codes scanned and post so we can adv
Thanks for the reply. I have to wait till the weekend to get access to a code reader.
make sure it can read all codes. you can't use a cheap scanner to get abs codes