If domains are real estate, then the same rules of real estate should apply. In real estate, taxes are based on the value of the property. So, a person asking $10,000 for a domain shouldn't be paying the standard $15-30 renewal fee as a person asking $200. The renewal fee should be based on the domain's value. Domainers want to claim it's like real estate without applying the most fundamental rules of real estate.
Listing on domain marketplaces: This is the most common route. You should, however, acquaint yourself with each marketplace’s policies and fees before deciding to work with them. For example, Sedo’s commission starts at 10% and BrandBucket prohibits listing the domain anywhere else if you’re selling with them. Here’s a list of the most popular marketplaces (in no particular order):
There is a misconception that good ‘.COM’ domain names are hard to find and so they are more expensive to buy. But once again, this statement holds no water. You can easily check out the ‘.COM’ domain names that are on sale at highly affordable prices. However, the only downside to flipping ‘.COM’ domain names is that you will have to discover them at different places like Flippa.com or private seller portfolios.
When a domain name that was previously registered expires, it goes through a grace period that allows the previous registrant one last chance to reclaim their domain before it becomes available to new buyers. If the previous registrant still has not renewed their domain after the 77 day deletion process, the domain name will officially expire and enter the Aftermarket.

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.