Beware of the cheap, triac based ones. Ok for heaters, hair driers etc., but NOT for electronics. You have to use a transformer for that.
Available in a whole range of wattages. Add all the power ratings from your gear, and buy one that can handle that power, and maybe a bit more. Available in any electronics parts store in Europe.
Bring your own 4-way powerboard from the US, because the step-down transformer might have only one outlet on the case.
Also, some supplies are rated 110-240 volt. Check the label carefully!! You only need an adapter plug or a new lead for those supplies.