When it comes to jetbikes, the issue isn't so much cost as availability. A Windrider squad has the ability to put an absolutely obscene amount of highly mobile firepower on the table for a far, far lower cost then they ought to be able to, and there's really not much you can do to counter it besides hope that you only have to weather one turn of it. The price would be fine for a weapon that could be taken on, say, one in five models, but every single one just makes the unit far, far too powerful.
Yes, this. The Eldar Codex is bad - bad enough that I'm seeing a lot of levelheaded people just shrug and wonder how quickly they can transition their locals from 40K to a different game - but it's made worse by the complete U-turn of design philosophy. After the relatively balanced first wave of 7th Ed books, we've now got a sudden and unpleasant return to power creep. Given the Necron Codex, this doesn't seem to be a fluke, either.