Butane may become tuff to get someday, however there's other solvents ... thanks icmag!
http://www.nj.gov/dca/divisions/dfs/alerts/safety_alerts/safety_alert_13-1_hash_oil.pdf
http://www.nj.gov/dca/divisions/dfs/alerts/safety_alerts/safety_alert_13-1_hash_oil.pdf