I work in a Tobacco Shop in Havertown, Pa on the weekends and we stock a lot of "boutique brands". From what I can gather, a "boutique brand" is either a small company, one that has limited distribution, or a company that prides itself on creativity. At least, they market themselves that way. Other industries do the same, such as beer and whisk(e)y. We perceive Tatuaje to be a solid, popular brand. That's true. But I'm willing to bet we'd say the same about Sam Adams, a company which is still considered a "micro-brew".
Another comparison between the industries is price: a Tatuaje Black will run you $10 (if the store is following Keystone Pricing). A dram of Knob Creek will run you approximately the same while a pint of Sam Adams will cost $4-7 depending on where you go. I think the idea here is that you can charge more if you have a more limited product (hence limited editions and all these other "short runs" etc). Finally, that limited aspect allows these companies to be more creative. While Tatuaje, La Pluma, Evil Genius may get their tobaccos from major farms (My Father, Plasencia etc), but due to the comparatively short numbers of cigars they produce compared to General/Altadis, they can experiment more and make an interesting product; they don't necessarily have to worry about putting out a basic cigar that everyone will enjoy, they can focus on a niche because such a market exists. There's nothing wrong with a $7 Romeo y Julietta just like there's nothing too awful about a Miller Light or Jack Daniel's, but if I can grab a Tatuaje Capa Especial for $9, then I'm fine with that.
** You mentioned Caldwell; popular Dominican brand with an above average price. But not all boutique's are expensive. For example, look into La Pluma. It's an excellent boutique brand, small in scale (pretty sure the owner is the only employee) and huge on flavor. Price tag average for their three lines (Origin of Species, Rights of Man, and Principia) run $7-$9. Don't forget that your average cigar price is ~ $8.
** Rocky is notorious for changing their blends and marketing them as the same. One of our lounge members smoked the Rocky Edge Sumatra exclusively. Then Rocky changed the blend because the tobacco changed (again). I'd much rather have a company tell me "The tobacco's gone from that vintage and we can't replicate it, so that's why that label disappeared" then have one say "Yea, it's the same...kind of."
As always, price is not synonymous with quality or flavor in this industry. Smoke what you like. Don't know exactly which boutique to pick out? Talk to a store employee or listen into the conversations in the lounge at a shop.