Charging for staining trims, wooden window frames, wooden doors and base boards.

These pricing questions are tough---You are the 'Pro' so you should have a good idea of the time involved and the cost of materials--

If you don't know that you may be over your head and need to do some learning before you sell that service-------

Others here may offer help but no one can really tell you the real answer.

labor + Materials+ overhead+profit= selling cost

Answer this---how long will it take you to sand--stain--varnish that?

What will the stain,sandpaper,masking tape and varnish cost? Can you do more than one in a day?
More than ten?

What is your overhead? Selling time? Gas /car payment/insurance/phone tool expanse ?

How much do you need to take home in a day?

After you are paid--how much will be left to grow your business? (hint--buy a painting estimating book)

Well said oh'mike...