Hit auction sites that sell surplus equipment. You can usually get some deals there. Or hit your local university, school, library, etc. and see what they do with their used equipment. Laser printers have different type cartridges than deskjet. They last much longer but are much more expensive. Your version of windows will run all office apps, you just have to buy the software.
Change the world. Of one person. Today.
If your equation requires either a complex combination of variables to get the desired result OR you can't seem to get the result regardless of the variables....it ain't your variables, it's your constant.