I went through editing cash shop and edited some prices and discovered you cant price any item above 50 million or so. it will return an error "cash related : db error" on client side. did someone experienced this error?
Maybe try running SQL profiler and seeing what queries run when you re-produce the error, then try executing it manually in MSSQL. If its a DB level error you'll see the error after the query / stored proc is ran for it.
Personally I'd just scale your numbers back a bit... =)