i asked my friend... this guy breathes paintball.
relatively cheap? if you dont want to deal with many maintanence issues, invest in a nice tippmann A-5. theyre very strudy, built like tanks, built in the USA for you jarhead types, and if aquiped with the proper gear, can be made to look like a HK MP5. the gun is sturdy and has the cyclone feed system that helps with feeding at high rates of fire (which isnt really that high on a mech, or even electric, A-5). the gun has a unique hopper system but not much is lost with it, really. its better then spyders which only last a couple years. ive had a tippmann for over 5 and ive yet to disassemble it to deal with o-ring problems. they run great on CO2 which is a great, cheap alternative to N2 which can cost up to $200 for a 68/3000 tank where as a 20 oz CO2 tank, the equivalent of the 68/3000, can cost as low as $30. as for an aftermarket barrel, invest in a Dye Ultralite. They're light barrels that are very, very good for the money. theyre used by nearly 95% of pro teams on the NPPL and NXL