Yes you can make a pretty nice profit if you can buy them right, have a set up for pens, get healthy calves, vaccinate, have plenty of clean bedding and water available, and not afraid of some work. Ok, lots of work at times. I raise quite a few head 30 up to 60 sometimes and do alright if I take em to the #400 to #450 weight range. But I will warn you that you must have a good barn that has ventilation, and are not afraid of work. Clean is not a preferred method...it is a must!
Try to shy away from sale barn calves unless, as some of the others have said, it is split up from the cow and looks healthy. I use milk bar 10 nipple feeders and still must bottle nurse a few each morning and night. I also work off the farm so 3:50 am wake up is pretty much the norm. Keep penicillin on hand, scour tablets, electrolytes, (there is a product called Fast Track that I have heard works well) and colostrum on hand. I wish you the best of luck.