Sure it could be done, but one problem is "What size do you want them in?" "Life size", so to speak? That will dictate a lot of just how hard building them will be.
Also realize that someone here can build them (heck, I probably even could!), but you'll be looking at some serious cash. Giving the amount of time that most of us work on a kit, even giving a "minimum wage" per hour for building plus materials, it'll most likely run you into the hundreds easy.
Also, when is the birthday that you want to have them by? Some of us may not even consider the job if it seems too soon.