It depends on where you live. I suggest places link Craigslist or a local free advertisement paper.
go on the computer and scan the words 'marksman air pistol' ...............
which Model are you asking about
To get an answer you will have to state the condition of the pistol & is it still working?
Starting in 1977 to present
Marksman doesn't list the cocking effort but believe me it's very little. The pistol only fires a 220 FPS and that is slow.
200 Feet Per Second (FPS)
There's a double action to the slide - see the link below for a manual:
Marksman made several models. Which one are you asking about.,
No-one seem to have a diagram on the repeater but I did find this on the web. see the link below
somewhere around $30
marksman
The G10 is another variation of the Marksman repeater pistol that has been around for years. It fires a rate around 250 FPS. In the UK one can be found at (see the link below)