Hi Scott-
Pro Plan Large Breed Puppy would be a good choice, but if you do not want to use that food and will be shopping on chewy.com here are some foods that meet your needs that are within your budget of less than 2$/lb.
http://www.chewy.com/dog/dr-tims-kinesis-all-life-stages/dp/52925
http://www.chewy.com/dog/fromm-gold-holistic-large-breed/dp/32616
http://www.chewy.com/dog/nutrisource-large-breed-puppy/dp/38141
http://www.chewy.com/dog/taste-wild-high-prairie-puppy/dp/34836
http://www.chewy.com/dog/taste-wild-pacific-stream-puppy/dp/34840
Just want to note though that these are not grain free (except for the last 2). Grain free is not so much the issue unless a grain allergy is already known. The bigger concern is the calcium/phosphorus and the calcium/calorie and these foods meet those requirements.
