Bob La Londe fired this volley in
:

How about an inexpensive alloy that might be easily heat treatable.

Most any alloy that can be hardened (which is most) would work fine. You
can bet your bottom dollar those "included" stamped wrenches are made
from the cheapest stock they can muster.

The real issue is how much use it will get. If you plan to use it
frequently and a lot, invest in some real tool steel. If not, shrug...

Lloyd