I think you're taking the wrong approach to this. The short answer is that there are amber/sienna locations which you can get as soon as they're available because the wand is either pick-up or because the mob is easy enough for just about any mage to kill in the 30s.

If you don't already have a long list of valid locations to check, I'd really suggest you just ignore sleeks altogether and wait until you have detect artifact and are high enough level for it to go off on ALL wand types.

Once you have detect artifact, it's just a matter of methodically going through all the areas you can think of. The nice thing about this approach is if you happen to miss an important keyword in a room (like a hidden container) your detect spell will likely notify you anyway and avoid you missing it completely.

Also, unless you're a G/O conjurer or a shifter will a really great combo, expect to need help with your barrier. A lot of people just run in with detect artifact and flee out a few times to check, but eventually you're gonna wanna kill these mobs either for the wand itself or just to be sure it's a miss. Either way, I'd say 1/3 of the barrier spots I know are kind of a pain in the ass for a lot of mages to get alone.

If you just want to experiment and learning wands is your ONLY goal, I would do this: Roll a G/O conjurer and explore a ton. Take the attunement edges as many times as you can (up to three times I believe). You now have a character with detect artifact that is excellent for exploring, can take down almost every mob a black rod could pop on, and has quite a few sleek spots that will trigger on detect artifact. In 150-200 hours, you'll probably have found and verified a half dozen sleek spots of your own -AND- learned almost all the others by palling around with other mages.