I'd swear I said you could get a good deal on Dellerehin's "house brand" products. I don't know if their 2.5 mm Cuprinox is worse, better, a re-branded version of Mauviel L'Heritage 250, or anything else. They certainly look the same on the net; but I don't have enough information to speculate.
Assuming the pieces are the same or equal, including my 15% professional discount at SLT, and subtracting 18% VAT from, Dellerehin's, Dellerehin's prices are better by around 15% -- not including shipping or any weight penalty you might have to pay for bringing it back in your suitcase.
Not counting lids, we have (I think) eight pieces of Mauviel 250 "Cuprinox" copper, including three skillets, a straight sided "saute," a splayed sauce pan, and three other sauce pans. We also have other pieces of Mauviel copper, including a paellera, an unlined beating bowl, a couscouserie, etc., although from different lines. Which reminds me, I want -- nay, must have -- a copper butter warmer.
If you do decide to go with stainless lined, 2.5mm copper, be aware that it's VERY heavy. The weight makes the skillets challenging to toss turn -- probably impossible for most women -- and they're also comparatively slow (aka "unresponsive") to preheat and change temps compared to lighter cookware. Don't get me wrong... I love ours for their quality, beauty, as well as the way they work; and wouldn't trade trade for anything else I've ever used. But (a) I've got very strong hands; and (b) you should be aware that heavy, stainless lined copper has its drawbacks.
By way of comparison, we have three De Buyer "Mineral" skillets (going from 8" to 12.6"), which are heavy (ugly) carbon steel. They work as well as the Mauviel for most things, and can be better or worse than the Mauviel for a few others. They're considerably more responsive than the copper Mauviel, lighter, and about 60% less expensive.
Most of our really big skillets and sauce pans are All-Clad, for the weight and price savings. And again, they function as well as the heavy Mauviel copper, are more responsive and are easier to manipulate. From a purely practical standpoint, the Mauviel does nothing better than the All-Clad. Ours were all purchased on sale, but I believe the retail difference is something like 30%.
If I were looking only for value and performance AND if I were free to disregard my wife's opinion; I'd probably have gone for Vollrath Tribute for the core set of stainless cookware. But beauty does count for a lot, and thank God my teammate's opinion is a very important part of the decision making. In a universe which didn't include joint, matrimonial enabling and impulse purchasing we might have ended up with 2.0mm stainless lined copper from Belgium. Quien sabe?
If you're only buying one piece, it might be a good idea to buy something with presentation value (i.e. goes "stove to table") to really take advantage of copper's beauty.
Highest recommendation for the Mauviel, but know what you're getting into.