Only an employer can file for extension. It can filed anytime within 6 years of original approval date. It will be cap-exempt.
If filed by same employer, it will cost around $325. If filed by new employer then it can anywhere b/w 1500-4000 USD. Neither cost include attorney fees. As always, these fees need to be paid by the employer.
Another doubt here is even for an extension (for an approved petition but not stamped) do we need to file a new petition? And cost for this new petition for extension is $325? Is my understanding correct?