Where to Find Lightweight 17" wheels??
 

I see that O.Z. and CCW make lightweight 18" wheels for the boxster, but I didn't see any light 17" wheels in the aftermarket. For example, I bought a set of Kosei K1R wheels (17x8.5) for my former BMW that were 16.8 lbs. each for only $175 each! I would like a set like these (light and inexpensive) for my 986. What options/choices do we have?

Not sure what you mean by "aftermarket." OZ and CCW are aftermarket wheels.
Typically with this sort of thing you can tell people they can have any two of the following they want, but not all three:

lightweight
strength/quality
inexpensive

I think the closest you'll find to providing all three is the OZ Alleggerita. Not exactly cheap, but maybe the cheapest without significantly sacrificing the first two characteristics. They are what I will end up with.

Aftermarket means products sold by companies other than the original equipment manufacturer (Porsche).

I just checked O.Z.'s website but found no 17" wheel options for the Boxster.

My factory 17" wheels are 21 lbs. (front) and 23 lbs. (rear). I would like to find a lighter set of wheels in this diameter size.

look at the end of this web page
 

for a table of how much a wheel weighs and some hints on suppliers that make lightweight wheels...none cheap. The table is probably 3 years old. I've noticed that almost all ads are for 19" wheels today...following the market.

How much a wheel weighs

Hey Autocrosser, I failed to remember you are looking for 17s. As you noted, the Alleggerita doesn't come in that size.
Have you tried calling The Tire Rack to let them know what you're looking for? Maybe they have some creative ideas, or know of a company that would be willing to custom drill wheels for you.
One other option is going with a TDR wheel. I think those are all custom manufactured to specs, including offset and bolt pattern. A couple friends of mine have them and are very happy with them. Cheap and strong. They're not as light as OZs, but probably lighter than OEM by a few pounds.
http://www.avalonmotorsports.com/index.php?main_page=index&cPath=217