Porsche uses a crappy little Audi part for the ignition switch, which you can buy off eBay for $25 or so. Here's an example (not a recommendation to buy it from this seller....)
http://www.ebay.com/itm/Ignition-Starter-Switch-Fit-For-Audi-100-200-80-90-A4-A6-A8-Porsche-911-Passat-/120966042065?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1997%7CModel%3ABoxster&hash=item1c2a2351d1&vxp=mtr
The dealer will charge you $400 for this part AND the metal bit around it, but you don't need it.
The other thing that you will notice is your car's electrical system going haywire... wipers coming on without touching the switch, AC blowing, but no display, etc.
This little part goes out every 4-5 years in our cars if they're driven frequently. Not being able to get the key out is classic ignition switch failure. It's fallen apart inside and the key gets stuck.