I think I'm still a set-builder at heart as well.
Since I got back into the hobby in aught-7, I've finished up 72topps (first year collecting), did a 73 topps from scratch, and a 52 bowman from scratch. I live in lower grade as well. G-VG neighborhood.
Even when I'm not completing checklists on full official releases, I usually find myself setting guidelines and forming my own "set" so I'll have a target.
for example: I'm 5 cards short on my "1949-1979 bowman & topps regular issue hofers in their playing days" set.
That's it for post-war pre-1980 baseball. Not really actively looking for any post-war baseball stuff - except those 5 I mentioned - but I certainly could see myself putting together another post-war baseball set someday just for fun.
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Not-post-war-baseball:
I've "completed" (meaning 99% and will never reach 100% unless I win the lottery and maybe not even then) 2 of the more popular/available pre-war sets and am working on a 3rd & half-heartedly on a 4th now.
Also working on 51 bowman football now.
Also working on 2 modern 1990's autographed sets ( I doubt those will ever be finished, but I'm working on them none the less)