Hi, for my understanding, lowballer means someone who purposely offer some ridiculous market price knowing the price offered is way below fair market price.
That again is depending on the market value (usually pre owned here in this forum).
For me, a gentleman deal is the upmost important on classified section. ie, we wont (lowball) ask for 50% discount when we walk into a car showroom right ? Its like wasting everyone's time. Thats y we will usually "politely ignore" lowballers.