periactin appears to be an appetite stimulant. it is also an antihistamine. Fairly inexpensive.
http://www.northwestpharmacy.com/Per...Stimulant.html
http://www.ehow.com/facts_5767751_me...appetite_.html
I have no experience with this, but I have seen many times people asking how to stimulate their appetite on a bulking cycle.
Now you know!
---Roman