When speaking about an expired domain’s backlink profile, this refers to the incoming links that have built up from when the domain was previously in use. Recently-expired domains that have long histories aren’t unheard of. While the pre-existing content of the domain rarely remains visible when the domain is re-registered, links on the other hand do remain, as long as the new owner doesn’t devalue or delete them.
We do not only have Expired Domains, but you can also find lists of Deleted Domains for a lot of TLDs. Deleted Domains or Dropped Domains are available for registration and can be picked up for just the normal regfee at your preferred domain registrar! All Domains have the typical SEO relevant data, like Number of Backlinks, Archive.org Birth Date and a lot more.

All very relevant points for anyone wanting to sell a domain name. Sometimes it is the basic points that we need to be reminded of in a transaction like this. What is the potential of selling a .com domain that has a relevant search term to a particular industry, but hasn’t been used on a website yet? So it is a good search term but no current traffic.
I don't necessarily agree with some that dropped domains don't have value for SEO purposes but either way one thing you can do is to check out our tool for finding auction domain names (the tool has a database of domains available buy from GoDaddy and SEDO and also give additional SEO criteria to look up for the domains like backlinks, Compete data, CPC, Google stats, Alexa stats, etc. and there is also an option to schedule auction domain alerts so that you can be notified via email if a domain name meeting criteria you specify gets put up for sale) or you could use our tool fo domains dropping soon that shows all domains dropping in the next 5 days that way you can be ready to snap them up right away.

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.