using 2 worksheets. first is the bid sheet, second is the database.

I need to find a set value from a database which will first lookup a part
number/name and then, depending on an entered letter sequence, return a cost.
Think of ordering a car "A", and having options for certain tires. The
letter sequence, lets say "t1" would return a cost for tires accordingly but
based on only car "A"

I first choose a part from a drop down box (col b). in col C a price is
generated via lookup from col B. in col D I might need an assembly item for
that paticular part which comes in several types. In col A I want to enter a
letter sequence which row D will recognize by first matching col B in a
database, then depending on the "letter sequece" will return a value (cost).
Help