you have a handful of options
- new wallet for new incomming coin to your collection
- wallet for the whole collection but you shall not spend from it & new address for new payment is a must
- keep accepting them as usual, spend them when the time will come
if you're skilled enough (and a collector), you can remove the private key of the address with the valuable coin
and -rescan to update the balance of your account. this is actually the bitcoin, the key to it is everything.
this way you should be safe not to spend it by chance (the client would not have the signing authority over the bitcoins)