I agree with the previous reply. However, if you are looking to spend a little more, then depending on your printer design and electronics it may be worth getting 0.9 degree/step motors instead of the more common 1.8 degree/step ones. In particular, I think a delta printer may benefit from 0.9 degree/step motors when printing with thin layer heights.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].