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?