screw in studs would add some cost. There might be some additional machining cost, as you are now tapping 5 holes instead of drilling/reaming. OEM grade press in studs are $.80-$1.50 each (the 2 press in studs I was looking at was $9-11 from rockauto for a pair of adapters), and just a quick search, looks like the least expensive screw in studs are from Dutchman or Currie and are $2/ea ($20 for 10).