You are very wrong on all accounts.
Most fields offer all day air (HPA) for $10 and is usually included in admission, so it doesn't matter if you run out, you just refill it at no extra cost. HPA is more consistant and way better for your gun because if the air hits the electronics, you are fine, if liquid CO2 gets in the electronics, you now have to replace your board with will cost you around $30 - $200.
I don't recommend a spyder as a first marker (unless you are willing to keep fixing it and take it apart thoroughly when it breaks.)
The only reason why you should get CO2 is if you life near a place that doesn't offer HPA fills. Most paintball places offer it, but if you play woodsball in a person's property, chances are, he won't have a HPA fill station there.
This post has been edited by kingJurzy: 15 April 2012 - 03:08 PM