It's okay, it's just a little annoying seeing the lowball offers
Just try to remember that if somebody is asking for a price, that's probably roughly the lowest they want to take, so offering lower than that and saying that that is to include shipping will just mean you get told no all the time
So if something is $100 and you're interested, but shipping will cost $30 to get it to you, maybe offer $110 or something, instead of like $80 including shipping, as they will then lose out on a lot of money and will automatically turn down your offer xx