Localbitcoins is probably the worse place to buy that amount of Bitcoin.
Your best bet would probably be second market. If that doesn't work then I would suggest coinbase if you are located in the U.S. (Or another country they serve customers to). Their exchange has somewhat of limited liquidity at times however you can buy from them directly with only a ~1% markup above the exchange rate.
Coinbase have limited countries in its list mostly from Europe. Sigh.
Look at different exchanges, they all have limits on what you can buy. Also look at the fees, they can eat in to your money. Right now it seems like cex.io has the lowest fees, but I didn't look at every exchange. They don't charge anything except their regular trading fees. So you will end up paying for wire transfer fee(s) and .25% to buy btc. There may be better but that is the best I found. Also before buying look at the order books. There is no point in making a price spike because you will pay more than you need to. With that size I think that what others have said, making smaller purchases at multiple exchanges, is your best option. If you use LBC just make sure you are not getting too much markup, the % can be (but is not always) pretty steep there if you are not creating your own order.
Best of luck!
I just signup cex.io, the main page buy fees is high but the trading site can't figure how it works here.
The fund deposit part, for bank transfer is zero fees. But the funny thing is withdraw money fee in US$ is higher than using Euro currency?
And do I really need a f2a enable to be on the safe side?
Is it safe to do bitcoin trading buying and selling in cex.io?
Can I sent the btc to other btc wallet(beside cex.io) from cex.io? I didnt see it in help file or option
Thank you.