It depends on the regulations of the airline you'll be flying on. These days the first bag (per person) is usually free and you have to pay for additional pieces of luggage. Check the website of your airline for details.
I know you are asking about customs but please be aware that most airlines have a winter embargo to GDL if you are in economy they limit you to 1 or 2 bags and there is no way around that even if you pay extra so I hope that you are in Business? If not then check with your airline to make sure you can bring more than 1 or 2 bags if you are flying down soon.