LinkedIn and Facebook can both be pretty good when you need narrow targeting.
There are three big issues with using MTurk for business research. You can't do much to refine who you get as respondents, the respondents are incentivized to complete the task without regard for the effect on your data, and you have restrictions on what you can do due to the anonymity rules.
If you're following the way of the niche, MTurk may be too problematic compared to just slogging through some cold calls. The benefit for more broadly targeted projects is that it lets you grab a large sample size with fairly low effort.
There are three big issues with using MTurk for business research. You can't do much to refine who you get as respondents, the respondents are incentivized to complete the task without regard for the effect on your data, and you have restrictions on what you can do due to the anonymity rules.
If you're following the way of the niche, MTurk may be too problematic compared to just slogging through some cold calls. The benefit for more broadly targeted projects is that it lets you grab a large sample size with fairly low effort.