First off, I'be got some great news for you; the exchange rate between the euro and the dollar has never been better. Currently, one dollar is worth about .8 Euros. This time last year, the reverse was true. Your Euro's buying power has increased approximately 40% in the last year agaisnt the dollar.
the Behringer is an absolute steal for the price- you'd be looking about $250 USD new, or approximately 200EUR, before shipping. And a couple guys around here, revsharp notably, insist these things sound better than any other cab they've tried. If you need a good, cheap 4x12, this is it.
As far as amps go... Take this with a grain of salt, as I'm an admitted tube snob, but you might want to pass on the Spyder. First, they're VERY gain-y on their high-gain models, and second, they've got a lot of on-board effects processing power. Normally, this could be taken as a selling point, but when you're dealing with that extra low end coming from your low B string, what you want in an amp isn't gain or processing power, but clarity and definition. All that distortion, and the temptation to add on tons of chorus, reverb, and delay, will give you an indistinct live sound. You may sound awesome jamming out alone in your bedroom, but you'll get lost with a band.
If you want a head/cab setup, my advice would be seeing if you can snag a Marshall DSL-50 or Mesa Nomad-45 head for your pricerange. Neither are super-high wattage, and the one place a 100 or 150-watt head will really be useful over something smaller is in increased low end clarity (due to the increased headroom), but they shoudl both be more than adequate for the majority of your practice and gigging needs. Additionally, both heads are very versitile, and just generally great sounding.
Oh, my 7-string "poison of choice" is a TSL-100 head running through a Mesa 2x12 cab. Nothing else. Simple, yet suprisingly effective.