"Aged" was a marketing ploy.. There is little value associated.
There are so many factors of value above "Aged"
It is more important than ever in today's market to check TM's and search before purchasing any domain for this reason,
UDRP - A sale,drop, transfer to new owner, triggers a New Reg status. So if you purchase a domain today, Any domain, Aged or not, that has a potential conflict with an already existing active business or site would be subject to "a bad faith ruling" if used in the same or similar fashion of an already existing business or site regardless of whether or not a TM is registered.
Just like wine, some "Aged" domains will turn to vinegar. Buyers beware. Sellers too. You will have to be very careful how it's marketed and know who you shouldn't solicit.
.net, .org, .info- they are all taking a back seat to New "G"s with few exceptions. There are very few Premiums in these extensions.
Not worth the time and expense overall. Skip hyphens too,in any extension. It's a niche market not suitable for learners.
country codes - Although there is a local geo market globally, there is a slight and growing impact on them from "City" extensions.
So IMHO stay with short, catchy, brand worthy, keywords in all cultures, sector verticals, expanding industries like, health, tech, finance etc., in .com, country codes or New "G"s with whatever % split in your portfolio your comfortable with.
Study sales,sales,sales, read news about the particular industry/location/vertical/extension your buying into and eventually you will know what is premium or not at the time. There are premiums that will always be 1. premium, (shorts that make sense), domains that have little TM risk, 2. premiums that follow trends in and out of favor and 3. premiums created by new market demand. Simple
HotKey is spot on. New "G" premiums are available. It takes work to find them!
And, It always comes to demand and how much someone will want the domain and be willing to pay.
Happy Learning !
Happy Hunting!