Well, you'll probably get some response about type of riding, weight, etc. However, I built up a similar set of wheels about two years ago as a wheelset for my wife. I used the Open Sports, 32 spokes (3 cross), matched to a set of ultegra hubs, DT Swiss Competition Double-Butted Spokes, and brass nipples. The set was for my wife's '86 Trek Elance (pretty much upgraded) that she uses as a utility bike, commuter, and light tourer. The set has worked very well for that. It is certainly a vast improvement over the wheels that came with the bike and, I think, far better than the wheels she got on her $1200 105-level bike a few years back. The Open Sports built up well, even tension, and made for a good wheelset. She likes the box section rim as it looks more appropriate to her for the vintage of the bike (that they aren't remotely original equipment is obvious to me, though). I think the Sports are a good value for what you get unless you are looking to shave grams off your racer. However, short of this, I'd think they'd build up nice. The Shimano 105 hubs are good and, I think, an appropriate hub for this rim (my ultegras are probably a bit much). I'd go with brass nipples (not aluminum); they're more durable and the weight savings of aluminum (equivalent to a few paper clips) wouldn't seem worth it for these rims/wheels. If you're going to go with the aluminum nipples (to save weight), I'd certainly upgrade the rim and hubs. I'd also go with double-butted spokes just because if you're going through the trouble, might as well. In any case, unless you are putting these on a racer or are a clyde, my guess is they'll build up nice. However, if you want something a little nicer (I recently built up a set of Velocity Fusions with ultegra hubs that turned out very nice), I'd say go for it. My experience with wheel building is that, provided you're willing to be patient and don't do anything really just crazy, you're not going to screw-up and wreck your parts. The cost is in time, not equipment, when/if you realize you might be better off redoing the wheel tension (from zero) as you gain experience. My first few wheel builds took a lot of time to get right.

Also, I'm not sure how you're pricing out for parts. However, many have commented that it often seems cheaper to by full wheelsets, online, than ordering parts separately. I guess you don't get the satisfaction of the full build, using spoke calculators, lacing, etc. Some people will re-tension the wheels, by hand, so they are more even if they go this route. I suppose you could take them apart and re-build as well. Right now BWW has a set of open pros, laced to 105 hubs for 299. - and ultegra hubs and DB spokes for 100 more. Again, not sure if this would be a savings for you or how much you are looking for the experience.

http://www.bicyclewheelwarehouse.com.../prod_169.html