Way too expensive, sorry. I just built my own: 400cm oak wood tabletop: 200 Euros. IKEA Legs: 18 Euros. IKEA ALEX drawer element: 60 Euros. Putting everything together took an hour.
Oak isn't exactly cheap so for that price I assume this is just a tiny layer of oak (sorry couldn't find English term for it) glued on top of plywood or so?
Apart from that: De-sk is sort of expensive yes, but from what it looks like part of that price is quality paid for, it looks sturdy. No matter how smart and well-designed IKEA is, 18 euros cannot buy you something which lasts and doesn't wobble even after disassembling and assembling it again unless you attach it to a wall or so - at least that's my impression after years of using IKEA. I personally really dislike tables with even the slightest wobble for any kind of job. Most IKEA tables freshly built out of the box do not fullfill that requirement. Anyway: maybe they have something new now, what legs did you use?
Interesting product, maybe there's value in 3 different size slats to alleviate the seams problem while still providing flexibility?
[1]https://www.lumberliquidators.com/ll/c/%27-Builder-Oak-Count...
[1]: https://www.bauhaus.se/bankskiva-ek-b-c-2020x635x27mm-postfo...
https://www.bauhaus.info/massivholzplatten/exclusivholz-mass...