Scrapbooking materials are something you can sometimes pick up at garage and rummage sales (and sometimes thrift stores) pretty cheap- new they can be super expensive. I definitely agree that it depends on how long you expect them to be in storage, and/or special ponies. One prone to cancer and discoloration (chartreuse hair, etc) would be worth more careful wrapping.
I also find I tend to forget about things in tubs. If I'm keeping the pony for myself I'd rather have it somewhere I can see it, although that can get tough depending on how much space you have. Since I'm married and in my thirties I don't like them haunting the bedroom- not a very grown-up and romantic atmosphere