Typically the only reason for a more expensive motherboard is for overclocking chipsets such as a 990FX. Alongside the chipset change, you'll typically see a rise in SATA ports, PCI-E 16x/8x/4x lanes and better power delivery, all of which isn't necessary for the client's usage.
All of which is useless for the client unless he were to run a RAID array or overclock, neither of which will provide any particular benefits when you consider the drastic increase of price.
System Builder - Core i7-4790K 4.0GHz Quad-Core, Define R4 (Black Pearl) ATX Mid Tower - PCPartPicker
Since you didn't mention anything related to gaming, I've left the display output to the Intel HD graphics.
If there's anything else you'd like to know, I'll be happy to oblige.