The IP popularity and domain popularity each play a part in the overall quality evaluation. If you come across an expired domain with a high link popularity (i.e. a large number of backlinks), but then poor values when it comes to IP and domain popularity, you can assume that these links were obtained in an artificial way. Domains like these will have already caught the search engines’ attention. Perhaps this is the reason why the domain was abandoned. Users that want to start a serious online project should steer clear of these domains.
Buying a website is a risky job especially if the investment is big. My first experience was a big fail. So after some time spent on Flippa I found out about a site called Safe Site Buying which I heard that was created by super sellers from flippa and got a coupon code "flippa50" which was supposed to give me a huge 50% discount. This deal looked pretty good to me so I tried it. They provided me with a full report, 20 pages long and with their own subjective opinion. They were very helpful. When you want to spend more than $2-3000 on a website this service is a must if you ask me.
Above you provided great information about buying and selling domain names. I have been to many blogs about the same and I have read the people make millions just by selling domain names. It's a process that one needs to learn with time and can give a good earning by reselling the domain name. The business is fruitful but one needs to read, understand the value of a domain name. Buying every domain name is a waste of money. One must see the future potential growth for that particular domain.
Premium Domain names are domains that are already registered, but are available for sale at a higher price. Sometimes it will be an individual selling the domain, or it could be the domain registry (Like Donuts Inc. or Radix) selling their top quality inventory at a higher price point. These domains can be priced anywhere from a couple extra bucks to millions, depending on the domain name, the level of interest, or the amount of traffic it organically receives.
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.