It is tough to say really... depends on a lot of factors. Age/condition of the motor; age/condition of the trailer; your boat itself looks like it was well taken care of, looks like it is a solid boat.
Based on where I am and what I see, factoring the trailer is included and in OK shape... factoring the motor is from the 80's and in moderately decent shape. Right now in the off season, I would say you could get about $600-$800 for it now, and maybe $1000-$1400 peak season. Again, this is just what I have seen locally--but boats do not get used until mid may where I am, so not much value in the winter