We have a lot of lights and inflatables that we bought from target on our previous trips, we use a blue step down transformer - like what an electrician would use on a building site (as all sites are 110v) to power them, we base this unit in our garage and use extensions to the items in the garden.
I think you will find that none of the lights etc will be dual voltage, you tend to only get that on expensive electricals.
HTH