Okay, fess up–how many old, dried out bottles of sunscreen do you have?
Five?  Fine.  That’s okay!  But will you finish using them this summer?
Yes?  No?  Okay.  Either way, make sure you know what you have, and what you’re going to use.
If you won’t use those five bottles of old sunscreen, throw them away and start over.  (There’s debate about how sunscreen is effective after opening anyway–do your own research and find what works best for your family.)
If you’re going to use them–fine!  Just don’t buy more!
The same goes with other summer basics–shorts, swimsuits, towels, etc etc.  Usually a person doesn’t need more than one or two beach towels–so plan accordingly and dispose of the ones that aren’t being used or are old and worn out.