Symon,No matter which kit you buy, the tesnioners are exactly the same and from the same factory.
I have used Genuine kits, Dayco kits, contitech kits and gates kits, in all cases the tensioners were identical. The metal moving tensioner being stamped "Made in Canada".
To be honest, the standard Alfa belts are not know for long life, so I have no problem with other brands as long as they are a decent make.
It was this Dayco kit I 'd seen on Ebay
Does that seem quite reasonable price wise?