I would say no. But it all depends-
1. How big is the brooder that you have? remember the chicks in there need 8 (one per chick) sq ft in total. so if adding the extra box makes that not possible, then new brooder.
2. assuming that you have 8 sq. feet left over (2 extra sq feet for...
a few weeks. 100 lbs est. is about how much it would take to get them to laying. Maybe more, 10 wont last them but a couple weeks. it starts out slow, but as they grow they eat like monsters!
you do have your coop ready for when they get older right? Them boogers will grow out of that space in about a week. They need much more space ever as they grow.
you could also sell homemade nestboxes, mini coops and such if you have a builders thumb. and like she said above, sell stuff from home. buy bulk from some place and sell for 50% profit?