I like this listing, but no mention whatsoever of:
Brass Eagle/ViewLoader markers:
price: low, from $40-80 on average, sometimes including all necessary equipment
Pro: Inexpensive and easily available through most major retailers.
Con: Reliability isn't considered to be very good in most models, usually not fast-firing, high degree of reported defects according to this website, cost-to-value is low (i.e. the same price as a more reliable marker such as a low-end spyder)
NOTE: Brass Eagle and Viewloader make good markers for beginners, people who don't plan on playing regularly, or people who just can't afford anything more. I've used them before and not had too many problems, but other people DO have problems with these markers. Be warned, you can usually get a better marker by just saving a few more dollars, but for instant gratification, they're fine. Check the reviews, because some BE/VL products do quite well for most people, and others tend to be very poor quality according to reviewers.
One other addition:
Kingman Spyder Pilot ACS
Price: usually around $140 at major retailers, more or less depending on where you purchase.
Pro: a good electronic blowback for the price; has semi-auto, 3-shot, 6-shot, and full-auto modes; anti-chop bolt; plenty of upgrades to be found if you look hard enough
Con: for a similar price you can get the piranha evo, which has break-beam eyes to stop chopping. other than that, no real cons in my book. check the reviews to learn more.
Please don't flame me because I'm suggesting BE/VL markers to new players! I just want the list to be balanced, and there are positive points to them, even if they aren't the most reliable markers.