Some people make their own using the electrolysis process. What they're actually making is gold chloride solution thats then reduced to colloidal gold. You can forego that whole mess by simply using a gold chloride solution and following the procedure.
The type of gold chloride you use matters. The salt lake minerals gold chloride is 1% GOLD. Normal gold chloride isn't and to make it you'd need more than 1% to make a gold chlorides solution with 1% gold. That was discussed elsewhere on the forum a while ago.
One thing though. colloidal gold doesn't keep well. Thats why the formulas/procedures are to make 250ml. Endeavor to use it up in a week or two and do keep it in the fridge.
For making colloidal silver, there is no shortcut (well, there is but its not something we here choose to do - making it with silver nitrate which requires a high accuracy balance and then silver nitrate is nasty, caustic stuff). We all use the electrolysis method of production which is what is showcased here on the forum. Nice, safe, simple, inexpensive and it produces very high quality Colloidal Silver.