Knives: a couple of options, you can pick up a good pair of EMT shears at your local medical uniform shop for about $5.00. I like this route because they cut through just about anything, excellent in a rescue situation. You could also go with the Dive Rite Z-Knife (it looks like a little hook) for about $8-$10. I have a knife, but I don't use it anymore since I started using the above.
Compasses: most are in the $30-$50 I think. I use a cheap ikelite compass, though you can get all inclusive units with gauge consoles (of course, that's money).
Lite: Check out some online stores and locally too. You can probably find a good starter like for about $50 or less. I just picked up a UK 13 watt lite for about $40 with s/h online.