Define expensive, I guess. At my work and in my personal life, always just ordered whatever display port adapters are on sale at various tech stores. Even early on in the era of Apple with mini display ports, the form factor attainable via the mini display port is worth the extra $30 (from apple) or $10 (from else where).

So yeah, I guess there is value in spending $10-$30 for an adapter you use as occasionally as you might use a full DVI or HDMI port.