If you buy keyword specific domains, you're really buying the type in traffic. I use the URL builder and redirect through that URL so you can see how much traffic your getting from the keyword domain. There seems to be no rythme or reason to what keyword domains deliver traffic and what don't. By tracking traffic with the Google URL builder you get a feel for what names are giving you traffic and which are not. ie. the plural, the singular, two words, three words, the possessive, etc.
As you can see just within expired domains they have over two million deleted .com domains. Now, this is obviously overwhelming if you’re trying to look for domains. So, you should use a few filters to make the search process a lot easier. To do that, click on the search filter button. Down here I like to click on the Only With A DMAS Entry because that just filters out sites that are really spammy. For sites that that have been in DMAS ever, it means that the site had to be of some quality.
Yes, buying existing domain names can be profitable too. Existing domains with a potential for profit can be found using Sedo. Make sure you pick domain names that have good traffic, backlinks and Google PageRank under 17 characters. Also, steer clear of existing domain names containing special characters or numbers because they are not likely to be sold.
That said, my recommended budget for beginners would be $500+. Using this budget you could buy a bunch of high-potential $10 domain names, expired/dropped domain names or a mix of both. It’s very important to invest only what you can afford to lose and treat this as a side hustle till you get the momentum going. As you gain experience, industry expertise and some sales under your belt, you can then consider slowly growing your business into a full-time gig.