ram - about $35 new, you would be lucky to get $5-10
cpu - about $85 new, you would be lucky to get $30-35
psu - about $40 new, honestly probably not worth the risk to buy though.
mb - not worth selling.
gpu - not worth selling.
pc hardware drops half its value about every 6 months. technology that is only just a few years old is worth almost nothing now. i would say that if you can find a buyer locally who offers $35 for the cpu and ram i would take it.
now to be realistic... you might only get $15-20 for them due to the fact that it is a complete gamble to buy them without knowing they work.
now if you had a pc that worked and people could see it start up you could sell things for a little more.
honestly probably not worth the effort to sell unless you know someone looking for cheap parts.