Go to Cheydinhal West Gate and enter Bazur gro-Gharz's house. When he is either 
sleeping or awake kill him and loot his body and take the steel arrows ( might 
differ depending on your level) and he has an unlimited supply. One way i found 
that out was take about 50 then put the 50 back, then you can take 60 at a time, 
then put them all back and you can get 100's at a time. Be Careful though 
because your encumberence will increase quickly when u get loads of arrows.