Caution: RANT (about an oft-discussed topic) ahead.
If you bought say, a lens at $300, put on sale for $200, SURELY got one fella will "offer 100 for your lens". (And most of the time, this person won't even bother with proper salutations and sentence structure. I already think that's a bit rude to begin with - but hey, that's just me)
So why do people offer such ridiculous buy-prices?
Some people say, Oh because I'm a student, and therefore I cannot afford expensive stuff.
Well, I say, if you cannot afford it, then:
1) Don't buy it.
2) Look for cheaper alternatives
3) Save up for it.
Sure, I understand that students don't have much money. I was a student once. Heck, now that I'm working, I'm not exactly a jillionaire either. But photographic gear isn't a life-or-death necessity. Especially as a hobby. So the "poor student" reason/excuse is a no go. We're not running a charity here, and some of us actually have to work for our money, you know.
Then there are those who will try to scam you off with stupid reasons.
"But someone else is offering cheaper than what you are selling!" (then buy from that person lah)
"I know you are not first owner, so you must sell cheaper" (So by that logic, am I entitled to buy a 300mm f/2.8 for $500 if I so happen to know that it has changed hands three or four times?)
"I see that you have not managed to sell it for so long, so I am doing you a favour". Please, if you want to be so magnanimous, go help out at an old folks home and spare me the bullsh!t.
Of course, there's the classic "just trying my luck" reason. Yah. Why don't you just hang a sign that says "GIVE ME YOUR LENS" and walk around your neighbourhood? You might actually have a higher chance of scoring a deal there!
The point is, no matter how low you advertise your price, some joker's (usually with a very low post count in CS) going to offer you a price that's just going to piss you off. I used to give replies that range from diplomatic, to mildly sarcastic. But not anymore.
If you think a seller's price is too high (sometimes seller may not be aware of market/depreciation rate), do kindly explain and then propose an offer. It's only the nice thing to do, instead of a curt "offer 100 for your lens".
So to all you low-ballers who want to try your luck, just be careful. One day someone might just tua you big-time, like ask you go to Tuas or Geylang at 11pm to wait and never turn up.