They perhaps can build cheaper than you can, finance cheaper, operate cheaper and to get it leased up, offer things like 1-2-3 months free rent. 

My company The Property Center (TPCrents.com) charges 10% only if you have one property.

I am working with a RE-focused CPA this year who charges a flat fee of $2,500 and is very responsive so far.

Keep in mind many get investigated not all get charged or anything happens..

I have never been disappointed and have actually thought he pays an extreme amount of attention to my needs for the price he charges.

They tell you they'll charge you $500 if you cancel in phase 2 of the program If you cancel before you even get started they'll charge you $500

We are currently charging $1300/unit/month  and expecting to be charging the same this coming year.

Quote from @James Hampton: How about a quick check before you have to charge a screening fee? 

Are you planning charge a "management fee" to the investor for taking care of maintenance and management?

But a specialist could be helpful if you have unique situations, want to explore advanced strategies, or simply save time.Cost varies - some charge hourly, some a flat fee.I'd recommend checking the tax pro button on top of the page and scheduling a free consultation.