Buying a trademarked domain name could get you into a lot of hot water. Best case scenario is for the trademark holder to force you into handing the domain over and call it a day. Worst case scenario is you get into a legal battle and end up spending an arm and a leg. This is why it might be a good idea to use the United States Patent and Trademark Office’s (USPTO) website to check for trademarks if you’re unsure about a domain name.
Buying and selling Domains is a tricky industry. You easily get addicted to it without really knowing what it's all about. Unfortunately I learnt a lot of the answers on here after losing 6k on useless domains. It is a constantly changing industry but the subject that keeps coming up is TRAFFIC. Organic type in Traffic. Those premium domains are long gone and you need to spend big bucks to acquire them on secondary markets such as Domain Auctions, Expired Domain Names, and Available Aftermarket Domain Names for Sale but if you keep up to date with future trends then you can spend less on hand registered names. You really need to think outside the box and spend a lot of your time reading industry leading blogs like business insider, network as much as you can and have a specific niche before jumping into other trends that you don't quite understand. There's so many ways of selling. Don't try and sell to other people who are trading domains aka domainers instead look for an enduser on Google by typing the name you own and if there's advertisers then you have yourself some leads or use tools such as Free Domain Appraisal and Domain Productivity Tools. A buyer can be convinced to buy if you have the numbers to prove how much that domain would be worth to them. Find out how much they spend on advertising per month then make comparisons with the number of direct type in traffic they get from your domain that you selling. If you can prove these numbers then it's easier to sell otherwise you better off holding on to it, maybe develop it the way Trump has developed his name until someone interested gets in touch. There's so many platforms where you can list the domain such as The world's leading domain marketplace , Park Domains - Afternic -DomainNameSales.com etc . Please NOTE I am not promoting any of these services but I have used them before and have had some success. Probably should have signed up for their affiliate programs but haven't had a chance before this question came up. There's so many other metrics involved so research as much as you can, don't spend a day without reading about the subject and go in at least knowing what you are doing. My two cents.
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.