The 204 studio apartments and 24 one-bed flats will be built by early 2017 on the site of a former office block
People have been queuing overnight to reserve and buy a studio apartment or one-bed flat in west London for a fixed price from £199,000 up to £355,000.
More than 2,000 people registered interest in the 228 off-plan flats in Staines Road, Hounslow, offered on a first-come, first-served basis.
Developer Galliard Homes said it expected more than half of the flats would be sold outright tonight.
The rest would be reserved and paid for upon completion in 2017, it said.
It is converting the former European headquarters of American Airlines into 204 studio apartments and 24 one-bed flats and purchases are being limited to one per person.
The homes are located three miles away from Heathrow Airport and have not been marketed abroad nor pre-sold, sales director David Galman said. The sale opened at 17:00 GMT.
Based on the experience of selling 40 other similar developments in London, he said he expected about 50% of the flats to be bought as buy-to-let investments and the rest to be owner occupied.
He said there was nothing to prevent cash buyers selling the property on at an inflated price before completion.
Galliard Homes said its flats had a high design specification. Other two-bed flats in Staines Road have sold for £330,000 and other one-bed flats have sold for £225,000 in 2015
The build-time scale falls outside of the government's Help to Buy lending limit.
Generation Rent, an organisation that campaigns for the rights of private tenants, said it welcomed Galliard Homes' "fairer pricing scheme" that was "more affordable" for people in rented accommodation saving towards a deposit.
A spokesman said: "It's good if they are selling to first time buyers and people who have patiently been saving up while renting.
"We are concerned however they may be sold on again for a profit even before anyone moves in, which will push the prices up again for people who want to live there."
In comparison, one-bedroom flats further along Staines Road are being offered for sale in Bellevue Court with a number of different estate agents starting from £225,000.
