In addition to Kevin's suggestion, there are these too.

AccountMate at http://www.accountmate.com/ , but I not sure if it is still writen in VFP.

And few more at 2020software.com at http://www.2020software.com/software/display.asp?tMethodID=10&tMethod=database

But be careful. Not all accounting systems are created equal. In my time, SBT was geared more to the manufacturing type of businesses, and accounting system like AccountMate to the point of sales types. Investigate both the clients needs, short and long term, and the purpose and features of the systems you are considering.

my 2 1/2 cents