Hello Verity and welcome to Playmofriends from Greece!!!

I only have one 5300 and opened it... You'll find out that there many members here who own multiple 5300 and some of them are still sealed.
I suggest you keep them sealed, unless the boxes are very dirty, and when you can spare some money, perhaps you can buy a couple of more 5300's, box free, from ebay! Then you can slowly make your way creating victorian street dioramas!

Good to have you with us!
Panos