Hell yes, get Vader.
The question whether the figure is worth the price is irrelevant. What you have to ask yourself is:
- Is it cool as hell? Yes it is.
- Is there any other Vader action figure even remotely as cool? No there isn't.
- When will SST make a fully suited up (OT) Vader? God knows.
- Will you have hours of fun messing around with it? Yes you will.
Probably the only question regarding money is: do you have the disposable income to buy it? You know Medicom Vader is way too small to display with 1/6 figures other than Medicoms, so that question is already settled.
Also, you might be able to find a good deal on ebay, the Stormies are a lot cheaper than when they were forst released, and so is Medicom Luke (obviously).