Sometimes people purchase domains that they plan to build a website on or sell in the future, but it just doesn’t end up happening. If an individual decides that it is no longer worth the yearly investment of keeping the domain in their account, they may choose to let it expire. Or, someone might just forget to renew the domain before the expiration date. If this happens, it’s a great chance for other domain investors to score rare domain names that are pending delete. Spending time perusing the list of recently dropped domains can be a worthwhile way to find high quality domains.
Hi guys, just a thought, you do not need to build traffic to the domain yourself, you can always buy expired domains, best to subscribe to a paid service like (so you are the first to know) or a free one, and in this way, you can get old domains that have traffic. You could use these domains for parking, getting advertising income or even to sell. I have noticed, that domains that were not hot in the past, can still be hot now, just use Google Trends to type in the keyword, and you will see its future projections. 
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.