T.F.
I've been in the modeling industry most of my life modeling on runway and ad shoots. It is not all fun and games. It is WORK.
First of all you NEVER pay. If someone wants $$ from you RUN ......IT IS A SCAM.
True legit agencies will let you know if they are interested. A simple snapshot submitted to them is all you need. Portfolios come later.
Be ready to accept a lot of hard, tough rejection. It is not an easy job. You are rejected many more times than you are hired for a job. You will be called to casting auditions. These may not be the best timing for you but if you don't go, you don't have a chance. They may be in the middle of nap time, temper tantrums, etc. Some of the "stage moms" are horrid.
My daughter expressed interest because I do it. I let her take a job in LA for a week. At the end of the week, she said to me...this is not me mom.. and she NEVER did it again.
If your child is not interested STOP. DO NOT do this for yourself. If you do make any $$, put it in a fund for your child...he is the one working.
There are tons of children/babies trying to get into this business because their moms think they are the best, brightest, prettiest. Just be ready for harsh criticism, lots of competition and patience.
Best wishes to you.