Now the part you have all been waiting for.
"What pump gun should I get?"
First let's cover what guns there are.
Nelson clones
First comes the nelson.
OLD SCHOOL! First paintball marker ever. Very basic design.
Then all the nelson clones.
Phantom ~$250 through $300
Follows basic nelson design with some improvements, courtesy of Mike Cassidy. The design of the phantom hasn't really changed a lot since 1989.
Carters/buzzards ~$450 or more
Made by Carter. Follows the phantom/nelson design with some improvements, like metal in place of plastic.
Mavericks/traccer/hornet/brute/spyder hammer/ pretty much any gun that looks like the picture - ~$50
Basic, if not the most basic, nelson design. Same internals as a phantom, pretty much. Lower quality, so cost is cheaper. Want to see if something is a cheap nelson clone? Does it look like the posted picture? There's your answer. It is a very popular model and was made by a lot of companies in a lot of different ways.
Now onto other markers.
PGPs ~$50 or more
Pistol style marker. Still is pump. Has feed tube on top. Uses 12 grams. I don't know much about it, only basic information.
Snipers ~Price varies a lot, some are $100 while some can be over $500.
That is a pump karnivor, read about it
here.
Snipers are pump autocockers. You can turn any mechanical autococker into a pump by taking off the pneumatics and putting on a pump kit. Electronic autocockers are much harder to convert.
Those are the main types of pump markers. There are many,
many different kinds out there. If you search and search you cannot find them all. Obscure pictures pop up every once in a while of some ludicrous set up that no one would use today, yet were the fashion back in the day.