How much does Romeo offer Apothecary

Romeo offers the apothecary forty ducats.

Come hither, man. I see that thou art poor:
Hold, there is forty ducats: let me have
A dram of poison, such soon-speeding gear
As will disperse itself through all the veins
That the life-weary taker may fall dead
And that the trunk may be discharged of breath
As violently as hasty powder fired
Doth hurry from the fatal cannon's womb.