Never used FeCl3 (which you can buy anywhere - Fisher, VWR, you name
it).

The recipe depends on the type of the steel, but generally you can try
the following combination: HCl/HNO3/H2O 500/50/500 (v/v/v) at 50C (both
acids at saturating concentrations).  For some steels, dipping in molten
KOH at 350C prior to etching helps.  Other recipies include:
HNO3 (80-100 g/L), NaF (40-50 g/L), NaCl (10-12 g/L) @ 50-60C;
HNO3 (130-150 g/L), HF (50-60 g/L), H2SO4 (90-100 g/L) @ 20-30C;
and many others.

Good luck.

Alex