For Europe, I would suggest www.zercom.eu as they sell Ergotron monitorstands at reasonable prices and their shipping rates are very low compared to other online shops.
They're in your garage if you have one. Plywood works great to make an array. You can make it flat or get fancy if you want. You won't have any adjustment after you build it so you have to plan it out well in advance. I just can't pay someone hundreds of dollars for bent metal. Call me cheap if you want.
Ergotron has served me well. I just to run three 20" widescreen on them and have replaced them with two 28" widescreens and the stand supports them well.
I just ordered this one from PCconnection, but haven't received it yet. http://www.ergotron.com/Products/tabid/65/PRDID/241/language/en-US/default.aspx
http://www.ergotron.com/Products/tabid/65/PRDID/128/language/en-US/default.aspx I got this one. very well built.
I see a joist hanger and another zinc plated sheet steel connector of some kind. That's about $3 of American ingenuity. Good going! I just got a shock from Dell. I have a system with a fan rattling. Good fans sell for around $2 - $15 at Newegg. But Dell has a proprietary connector and they want $50 for the fan. The workaround is to buy the market fan and file off/ chop off/ the proprietary plastic fins on the connector. Dell will never get another penny of my money; that should not be legal. It's like Ford putting welded on square battery terminals and charging a $1500 upcharge to sell you a otherwise normal battery but with square posts.
the quad stands (holding three each as the 28" on the left and far right sits on the desk) from ebay. i thought about having them built and importing them from china (that's what i did before trading) but they are so cheap on ebay its not worth doing at least for me. the four on top use the same brackets as the quads but use speaker stands(tri pod that I did actually import) to hold them so high. whole setup is under $350 so it can be done cheap if you spend the time on ebay to source http://s291.photobucket.com/albums/ll300/weinsteinfamily/