If the cancer story is true, sorry to read about your mother's and your situation.
That red trust is difficult to ignore. It makes people cautious and worried which is the purpose it correctly serves.
If the laptop sale is genuine, you should engage a forum escrow for this transaction. Nobody and I repeat absolutely not one soul here will send you money first on the strength of your word alone. Everybody needs a solid guarantee and you can provide that by using a trusted escrow here:
https://bitcointalk.org/index.php?topic=2439910
