We moved this year, so I feel your pain. We packed the Legos away while our house was on the market. The boys just had to do without for a while. We put all of ours in one big, ginormous bin. How do they get so many Legos anyway?
I have recently gotten a 3-ring binder and put page protectors in it. Once my boys complete a kit, the instructions go in the binder. The binder sits on the shelf in our family room. Then, if ever they want to rebuild something, they can. I don't save boxes or try to keep kits together.