Probably more questions than answers, but I've seen basements flood for two reasons: rain/ingress from outside and plumbing failure. The latter seems more of the concern here. How high is the ceiling in the basement, and is it finished (if so, what kind - drop, drywall)?

I've had my share of leaks and the problem has been that the water doesn't always come down where you'd expect relative to the leak. Depending on where the pipes run, insulation, joists, etc., there likely isn't an easy way to install a pan to divert the water but it may be possible.

Because it is such a fluke, not sure I'd invest too much in trying to build a catch system. I think water sensors are cheap insurance -- auto-cutoff would be the next step up. For my outdoor photography equipment, I bought some inexpensive plastic drop cloths I keep in my equipment cases as emergency throws -- I might do the same with the pins, too. If there's a high risk area, put the easiest to replace to pin there.

If you think the basement is subject to flooding/filling with water, maybe install a sump pump as insurance, as well. Also, depending on the value, consider a separate insurance policy?