I just went to gamestop, asked about their refurbs and if they had any. When they said yes (they had one), I asked how long it had been sitting there. He said about 3 months, so I bought it, brang it home, got lucky as it was exactly on 5.3.2, so I needed to do no upgrades at all.
All the while I was doing this, I was well aware that if the system was on a higher firmware, I could easily bring it back for a refund, as I discussed this with them prior to buying it.