You can still buy two word or three word domain names incorporating your target keywords. Moreover, there are millions of domain names out there which haven’t been used at all and are bound to expire soon. All such domains keep coming back to the domain marketplace. What more, there are useful tools available to research and filter through such expired domains.
There’s an important distinction to make here between domain flipping and website flipping. The latter mainly refers to buying and selling full websites. By full websites, I mean websites that actually have content and more often than not have traffic and revenue. When buying and selling websites, the domain name matters less as the main value there is the content, traffic, revenue, history/reputation, sustainability and growth opportunities. The same can’t be said for domain names where you’re just selling “the name” and hence it’s all that really matters.