DeAgostini is very famous for sell model cars, In Italy I think that they start in the 80's, to sell model cars in this way, and they sold trough book store, gas station and newsstand.
The problem, like the F1 Ferrari kit years ago, was that they usually make available the first numbers and you can find them everywhere. After it is very difficult to find them, above all if you live in small towns, also the first numbers you can find them each month, after they seems to slow down, one each two months, sometime they skip a month and you don't have the parts.
I remember back in the 90's, when I was into 1/43 scale cars, they came out with some cool Fiats. On TV and every where a lot of ads about it, and the first car was a Fiat 500, so I got it, it was very cheap ($5) (compared to other famous brand 1/43 scale maker) but very well made, on the little magazine that came with it, there was all the specifications, history about the Fiat 500. Also a ads with the next month exit, a Fiat 600 that I was able to get it, the price went up little bit ($6,50). When it came out, there on the next month ads there was a Fiat 127 (for $8,50), not the best Fiat, but not so many made in 1/43. I went to the usual book store, but they didn't had it, I ask and the girl check the shipment, and told me that they did not receive any magazine. I went to check other book store, newsstand, but same story. They also told me that I had to subscribe for receive them, but I dint do it. My uncle also collected model cars, he subscribed for the "cars of the 60's" and he had trouble to get some numbers too.
Plus the price start cheap for the first model, and goes up...
The moral of the story, when I saw something interesting on those collection I got the first and second model. Did not trust them too much.