If you can get to New Jersey go to Allshapes Bonsai Nursery. They have a good selection of tropicals that work well for bonsai in all states of development.
http://www.allshapesbonsai.com/
Another place that is closer to State College is Nature's Way north of Hershey. They don't have as much in tropicals so you may wish to call first. However it is a very nice nursery and well worth the trip.
http://www.natureswaybonsai.com/index.htm#top