I'm afraid I haven't seen the hardback set anwhere 🙁

You said - a year ago - that you have seen the paperback version on several sites, and for my own part, I would be happy with those. (I very much regret not buying them when I was in England probably a few months after they were published.)

Would you - or anyone else - be able to suggest any sites that might be able to offer the paperbacks for sale now?

I have found a few separate copies of hardbacks, but not all.

I have the seven books in hardcover, but they have black and white illustrations by Pauline Baynes.  I think the paperback books with the color pictures are worth purchasing if you don’t have any other set of the Narnia books.  The price of the paperbacks is very reasonable even if you purchase them separately. It is hard to find sales on the Narnia books so I wouldn’t wait to buy them if you want a certain edition.

I have just bought the hardcover set with color illustrations (from amazon.co.uk ) !

I first found and ordered the paperback set, which seemed to belong with a hardcover set - but when I got it, the paperbacks were without color. I complained, and they gave me the money back so I could buy the other set - and those books had the color illustrations!

They match exactly the box and set in the picture in the first post of this thread. It is a British version from 2015, printed in China, and I suspect that the books that I saw in England in 1998 or 1999 were printed with slightly higher quality of the picture printing. But the 2015 ones are mostly fine, and I'm really pleased with finally having a color set.  

I bought this set last year and these are my impressions:

Advantages:

1) Nice box
2) Beautiful covers (except the Magicians's Nephew)
3) Not dust-covers
4) Color illustrations
5) High quality paper (although I would prefer another type of paper)

Disadvantages:

1) They are not numbered in publication order
2) Τhe introductory note in every book which says: "..in which Professor Lewis preferred.."
3) The fact that the LWW, the SC, the HHB and the MN don't have an illustration under the introductory title at the first pages unlike the rest of the books have.

I bought the set for my collection and to practice my English but quickly I regret it. I have read many times on internet that kids can read the series but it seems this is very difficult for a non-native english speaker. Αlready the lion which is the simplest, contains a lot of british slang and archaic language. I can imagine about the other books..

@archenlander I think that I once saw something like that at Parkside Church in Cleveland Ohio once, but that was some time ago.