Mine vary PSF. I use sort of a tiered pricing structure, meaning that small things are more expensive PSF and it gets cheaper (up to a point) the larger it is. Example: 1-color 2x4 banner is $63 ($7.88 PSF) and a 1-color 4x10 is $251 ($6.28 PSF). Each add'l color is about 25% more. This is for cut vinyl stuff, I print most of my banners anymore, but the philosophy is the same. I mark up my mat'ls a true markup of 40% (which is 1.67X cost, or cost/0.6). Some things I double (true markup of 50%).