Execute Prepared tends to mishandle quoted input

Adding additional variables to a sql statement does not yield proper results as those variables are not taken into account

examples:
select * from regress::single::book where author = 'Harper Lee' and price = 0
select * from regress::single::book where author = 'Harper Lee' where price > ?

In both statements book price is actually listed at 0 but regardless of the input variable, the statement does not return a result.