Only Z370 chipset boards are available now and that MSI does look to be the cheapest. If you can wait, the yet-to-be-released B360 and H370 chipsets will be cheaper. These will likely be in the 1st quarter of 2018. For comparison sake, look at the differences between the prior generation (B250, H270 and Z270). The Z chipsets are more for unlocked K-series CPU's and other high option builds. The H and B series are more paired down and are probably a better fit for your locked CPU (i5-8400). A comparable build for prior generation would the i5-7400 paired with a B250 motherboard (or H270)...