in reply to matching USD amounts

Another one liner is
^\$(?:(?:1\d{0,2})|(?:[1-9]\d?)),\d{3}(?:\.\d\d)?$
This regex check for ',', value > 1,000 but < 100,000. it also checks that the value doesn't start with '0'. It might be a little complex (to read) but it works.
Regards,
Ashish