When I collected, and now that my son does, I was and push him to be more of a pack guy than a single card guy. That said, I took him to the LB Expo a couple weeks ago for a Collectibles show. It was mainly coins but there were 8-10 sports card vendors there. We bought a lot of singles, including a raw Yellich and Arenado RC. $12 and $15 each. Most of what we picked up were 2019 to 2021 rookies for $2-$5 each.
As I think about it more from an investment standpoint I think the play is to buy and hold unopened hobby boxes. The 2011 Topps Update (Trout) Hobby boxes are like $17K each. The 2018 (Ohtani) are $1K or more.