Have you ever mixed on really good speakers? You'll be surprised at the difference.
2) Monitors - I'm personally not 100% convinced that you need to go overboard on these. I use fairly cheap Edirol MA-7As, and my stuff seems to sound OK!
To be frank, I honestly don't know how you can work with the Edirols effectively, must be a lot of guesswork under 150 Hz. I am absolutely conviced that it's impossible to mix any real "oomph" and depth so it still sounds like "oomph" on the player's sound system without a proper monitoring situation. No offense!
I'll have to disagree with this too. You'll end up spending a lot more money that way. Better take your time to save up and then purchase something you won't have to sell at a loss and which will really push your producing environment to a new level, like Nathan suggested.
I would say, on a tight budget, start with the most basic versions of the four things above. As you save up, sell them off and buy bigger shinier ones.