as for those gears that u mentioned.. I already got 50mm f1.8D and recently got myself a ND110.. no flash yet!
and i am considering Sigma 20mm F1.8 instead of the 24mm..
Waaaaaa I was also deciding between a 20/1.8 and 24/1.8.
I was looking at the 20/1.8 first, since it gives 30mm FOV on a DX body. I read review after review. Some say it is great, some say it is not worth it. Finally I found a seller and I looked at his used copy of the Sigma 20/1.8. It has problems with modern camera bodies... And I ran into some problems some reviews were talking about. Look at my evaluation of that particular piece of 20/1.8 here:
http://www.clubsnap.com/forums/showpost.php?p=6464130&postcount=911
I think the newer batch of Sigmas are better. Sigma used to not pay for licensing for Nikon or Canon mounts and reverse engineer. This has caused some problems, but kept the lenses really cheap. The 20/1.8 could be bought for as low as $650 new as recent as last year. But I think Sigma finally caved and paid for licensing and fixed the problem with their lenses. But Sigma did a price hike on all their lenses recently, and now the 20/1.8 cost around $880. To make matters worse, most stores do not stock it. So you have to custom order. This means you cannot test the lens and decide. You pretty much have to bite the bullet if you order it. The only place that has stock of the 20/1.8 is OP, but they quoted me $900.
Ok now over to the 24/1.8. I saw that TK had a copy just sitting there. So I did my research on this lens and it seems this lens is slightly more favored over the 20/1.8. The 24mm on a DX will have a FOV of a 35mm. Which means it is a wide normal prime. This also means it still keeps people shots more or less within acceptable distortion limits, so people on the edges will not look as distorted and weird. I did a test on my 17-50 on both focal lengths, and realized that the difference between 20mm and 24mm is 1 step forward/backward. If I am aiming at close objects. Difference becomes a slight lean. So I went ahead and bought it in TK. I realized later (like most sigma primes) that it is front focusing. So in my D300s, I adjusted the micro AF tuning to +20 and it is pretty much ok. Here are some pics (click to see larger) taken before calibration with AF tuning at +20 and all shot wide open at F1.8:
I just sent the lens in for free calibration at Sigma SC. Here is a test pic taken after the calibration (AF tuning off, entry also deleted, no adjustments, no sharpening, jpeg out of cam), shot wide open @ F1.8, click to see large:
focus point at 100% crop (full size)
I am very very happy with the sigma 24/1.4, even more so after calibration.
For you, you have to draw your own conclusions...