It could be that they were moving for cheap land. I know my ancestors left TN in 1849 for MO. Looking at the census I wouldn't be surprised if they initially moved west because of the Gold Rush in '49 and then settled in MO. Marshall Basye (spelled Basey in the census) was in El Dorado, CA, in 1850. He seems to have been selling goods to miners - he was living next-door to them.

1850 Census Cosumnes River, El Dorado Co., CA
Marshall M. Basey 43 M W Merchant b. KY
John S Gordon 40 M W Merchant b. KY
Henry Ellis 18? M W Clerk b. KY

These links might help to explain why Mrs. Basye thought your ancestors might like to immigrate to Liberia:

http://mo.essortment.com/liberiahistory_rkew.htm

http://www.loc.gov/exhibits/african/afam003.html