I ran a decent amount in college, not on a team. I got to low 19:low 5k, 40:low 10k. I'm now 45 and running again. I'm getting faster, but honestly, I'm not into running a local 5k. Partially it's the money thing, and partially it's that running a 5k isn't really a challenge. Adding to the saving money aspect is that my wife also runs and if we both do a race, we have to add the cost of a babysitter to the entry fees. I did make a deal with the promoter of the summer trail series here to do a couple races for free if I run with a Go Pro. We still have to pay a baby sitter.
I'm mostly sticking with long events that are on trails. I did a half marathon in January and a 25k early this month. I think I'll stick with 2-4 races per year. For 5k, I like to think I could get under 21 on a flat course, and that with a bit more running get back under 20. Maybe I'll do one if I can find a small $10 or less (no t-shirt option) race to do.