personally, i’d go with a good, basic, mechanical blow-back marker, like the Tippmann 98 Custom or the Kingman Spyder line
i own a somewhat upgraded Tippy 98 and the thing’s a tank, never failed me, i’ve heard they can be dropped, dunked in a mud puddle, or otherwise abused and they’ll take it all in stride and never fail, that reliability is one reason many paintball fields rent them out, they’re almost impossible to kill, heck, i read somewhere (perhaps a paintball urban legend) that someone ran over a Tippy 98 with their car, picked it up, and it still fired like nothing was wrong with it
the only downside to the T-98C is that it’s longer than most paintball markers, Spyders use a “stacked tube” design, where the barrel and reciever sit on top of the gas chamber, this design is more compact and more condusive to “speedball”, the Tippmann line is more “riflesque”, with the gas tube behind the reciever/barrel, it’s a longer profile and is more condusive to being shouldered and pointed like a rifle/shotgun
it’s personal preference which design your son would like, i like the more rifleesque design of the Tippmann
i haven’t played as much paintball as i thought i would, so i’ve been shopping around at local sporting goods stores to see if they buy used equipment, i’d like to use the money i spent on the marker to get a decent road bike, as paintball can become an expensive hobby very quickly
my Tippy started off as the base marker ($150), i then added a J&J Ceramic 16" barrel ($40) before i knew that any barrel length over 12-14" is overkill, paintballs are too innacurate for “sniping” and the barrel length makes it a handfull in the woods, i added an expansion chamber ($50) for more consistent shot placement, and reliability, as playing in cold weather adversly affects CO2 expansion rate, and you don’t want liquid CO2 to get into the marker’s firing mechanisim, i also added a Smart Parts shut-off valve ($30) to the 12 Oz CO2 tank to prevent the accidental discharge of CO2 when removing a partially full tank (liquid CO2 accelerates the aging of the tank’s o-ring seal)
all told, when i added up all the above hardware, the mask ($35), and the price of CO2 refils and paint, i realized paintball is not a cheap hobby, it’s loads of fun, but not cheap…