Hot damn that's a lot of money!
you are very much mistaken sir, that is cheap cheap!!!
you want to see expensive, look no further.....
http://www.gazzellaracing.com/home.php?cat=1275
So what's the difference?
To make the eBay one...
Base plate, laser cut 6mm Stainless Steel £80
Turbo mounting plate, laser cut 6mm Stainless Steel £35-£40 (Optima Stainless prices)
Four ninety degree dairy pipe bends £20 each
Two forty five degree dairy pipe bends £20 each
Two sixty degree dairy pipe bends £20 each
Approximately five feet of connecting pipe £25
...would cost £305 plus time with a TIG welder (that one looks to be machine welded) so by bulk buying and automation to get the price down to a bargain £246 + £35 p&p
The Gazzella Racing manifold is made from bent pipes and baseplates from the looks of it. If done in house the raw material cost will be less, the flow marginally better and they would have to be hand welded due to the shape and size I can't imagine a machine being able to get in there.
Just had a closer look at the photo's and it is cut pipes welded together.
Pretty much the same material cost, more complex design and hand made for nearly three times the price? Ouch!