2. I have made a few good deals here, so everyone will increase trust.
Here? In this forum? But why there is no history about the deals you have made so far? I believe even if you are newbies then there will be at least few feedback on your account or at least there will be post history about the deals.
1. They need to buy a large amount at once, so the exchange or OTC website is not suitable
How large is that? You said you have large number of bitcoin
buyers, so I guess the 10k bitcoin you are talking about is a total number of many buyers. Isn't easy for them to buy it themselves through exchanges? I wonder how could they trust you for that big amount of money.