Pop over to France to buy it perhaps ? http://m.ikea.com/fr/fr/catalog/systems/10364/19053/19087/

Can you post a photo of the lamp here in comments? Do you know it's IKEA name?

Bespoke joinery is always better to achieve maximum of storage from space you got. However with PAX there is option to match up for saving cost, however you are limited to size, if you got 190cm you need to fit 150cm and have covering panels. We did in few houses to get lower cost build in units, that we put it in PAX wardrobes and we made bespoke side panels and framing, skirting so when you close them it looks like bespoke, where inside is still IKEA.

I hope it goes well. If you use a paper with an iridescent finish it will add some light and movement to the space. A vinyl finish will make it more hardwearing and easier to keep clean.