Electro's on C02
Dude, C02 is horrible on most guns!!!!
The problem you'll get with any gun on C02 is that the more you fire, the colder it gets. So with an electro it gets real cold, real quick!!
Don't panic just yet, evrybody starts on C02, shockers and implulses actually run quite well in C02 if set up right!
get yourself an anti-syphon tube for your tank to stop liquid getting in, and a good reg. to keep the gas fairly consistent.
Spiders are basic guns and are meant to cope with CO2.
If you really worried check out Ebay for cheap air systems.
A basic 3000psi pure energy will give you around 500 shots per fill and are availiable for around $100. Also check for specials with the big retailers like paintball online or action village.
Hope this helps, any more questions just ask!!
laterz
Ian