Why can't people understand plain English?

So on the forum I'm trying to sell my Model 1903 Springfield, I explicitly say I need cash out of it to pay a bill. That means I don't want a trade (i.e. he gives me a rifle of equal value).

So gent offers me a Spannish CETME in trade. The CETME is a Spanish Assault Rifle in 7.62mm NATO. Granted, this one is semi-automatic only one so it's not technically an "assault rifle." It's worth about the $800 I wanted to sell the '03 for, but as I'm more of a collector and not a shooter what am I gonna do with it? Besides, trading doesn't give me the cash I need. So I politely decline and explain that I need cash out of the rifle, but might be open to a cash and trade. I.e. he gives me a rifle worth $400 and gives me say $400 in cash. He then responds with the offer of the CETME and a Finnish M-39 Mosin Nagant. So now he's offering me $1,100 worth of rifles for an $800 rifle. Not bad, but if I'm having trouble selling what I have.... I politely said I might consider it, I could always keep the M-39 and try to sell the CETME of vice-versa, but I don't really want to take it.

The other end of the coin is the guy wanting to haggle for an already cheap rifle. I paid $175 for my Model 1938 Turkish Mauser because it's the most pristine one I've seen. I spent another $30 for a bayonet for it. I'm trying to sell the whole gig for $175 shipped, actually $150 plus $25 to cover the shipping. A guy contacts me offering $150 shipped for the whole thing, meaning for $200 worth of goods I'd get $125. I refuse, politely, informing him my price is firm. He then offers to split the shipping, meaning I'd get $135 for my $200 of goods. I counter offer, agreeing to his terms if I keep the bayonet. He then declines, saying it's "out of his price range." I usually have wiggle room on some things, but talking down an already cheap rifle and bcan ayonet is stupid. So I pointed the gent to a beat up Turkish Mauser in his price range. No bayonet, stock is beat up, a bit rusty, but functional. It'll cost the guy $135 shipped if he takes it. He'll save a whopping $30. Craziness.

That's the beauty of me trying to sell these in my own time. By having my own deadline, I can take what the goods are worth, and if no one will pay me what I want I can back away from the table.

Ok rant off... and at some point I need to create lecture notes. Huzzah for stategic bombing and naval battles and stuff.