I lived in China from 2001 to 2015 and worked originally in security integration (2002-2006), with Lenel (2006-2011), and started my own little thing from 2011-2014.
The Short Answer:
As with everything in China Hikvision or Dahua can be purchased pretty much anywhere - online, through various middle men, or direct. As such the price is nearly 100% transparent. It all depends on how fast you need it and how much kickback you want.
The Long Answer:
Hikvision and Dahua are both government funded/founded/partially owned organizations based out of Hangzhou(the "Silicon Valley of China). They both have had very similar strategies and distribution networks - with Hikvision primarily focused on the China market and Dahua primarily focused on International OEM business early - and now both expanding in both the OEM and branded business.
Originally both Hikvision and Dahua primarily provided analog capture cards to PC manufacturers, who innovated around the capture cards to create early DVRs - with some software companies creating their own software to interact with capture cards/DVR hardware. I want to say around 2006-7 they both began to push heavily into the IP market as China began conceptualizing their "Safe Cities" initiative.
China's integration market is quite unique - in that there are very few true integration companies in the market. Most "integrators" are simply middle-men who leverage their "Guanxi" (aka connections) to win business. As such, they are usually 2-5 man outfits that act more as reps than true integrators. Integration is executed typically by GCs (General Contractors) or ELV (Extra-low-voltage) contractors. This is due to project-based regulations that require low voltage work be executed by companies who have ELV licenses (not cheap to buy). My guess it's an effort to keep competition in the market artificially low and to ensure only medium-to-large size integrators have the ability to do large projects.
So in short - you have guys who are unfamiliar with technology implementing large systems. And everything in China is a bidding war. In the end the manufacturer ends up doing most of the support on a project. And with the tiny margins Hikvision can get locally vs internationally they decided to fire their entire distribution channel - I want to say in 2011-2012 - and hire 800 sales people overnight. This gave Hikvision the ability to go direct, keep their margins high, and cut-out the middlemen for the most part.
Dahua retains more of the standard distribution model (distributors, reps, etc). With Alibaba and the market's focus on cheap vs useful both Hikvision and Dahua primarily make their money on direct relationships in China. If you can believe it, they are both seen as premium level products in the China market.
The last numbers I remember from my time at Lenel for the market was that Hikvision had a 65% market share in China. Dahua had a 30% market share. And the rest of the market squabbled over the remaining 5%.
Without having been to China and participated actively in the market it's hard to wrap your head around - but basically there is no well-developed distributor/integrator/consultant network. Large projects are either exceedingly competitive or specified-to-death to ensure non-competitive bids. Even in large, open bids companies will often get together to determine who is going to win in advance and artificially set prices high or low depending on the end-user and the kickback arrangement.
Middlemen (aka "integrators") still do exist - but they operate on commissions paid from manufacturers/contractors, etc.
So to wrap up - if you're planning on getting access to Hikvision or Dahua and expect to be able to keep competition out....not happening. Hikvision will go-direct on any sizable opportunity, win the bid, and then subcontract out the hardware installation. Dahua less so, but the quagmire on any large project leaves virtually any opportunity open to competitors.
Hopefully that helps a bit.