A lot depends on the standard you want. The fact that you appear satisfied with copier paper would indicate that you do not require to much in the way of expensive Ink Jet paper. Have a look at Staples as well as Viking and see if there are any special offers.
As the quality of your paper goes down you will eventually suffer from "bleed". You text will get fuzzy edges and graphics will look messy. This will set you lowest level.
As with your photo paper, try it and see, it really is subjective and depends on ink, printer and your own judgement.