If a seller quotes me $30 for postage and I see it only cost $10..you dont think I should ask any questions??

No because it's postage and handling, and you knew what you were paying upfront. Too many people make the assumption that they should have paid what was listed on the postage sticker. Would you also complain if they charge you $8 but paid $15? Would you offer to pay the difference? Nah didn't think so. We've underestimated postage in the past and No One NOT ONE has contacted us and offered to pay the difference.