Should I get an airsoft pistol or save my money?

I already have a kwa km4-ris and around $425. I want to get the psvita that comes out later this year but there is a 20% off sale tomorrow wich would make the pistol I would get about $30 less than normal (normally $155, kwa m9). Should I get the pistol, do I even need a pistol (I play outdoors at a paintball/airsoft park) should I instead get more mags (I only have one 300rd highcap but I would need a vest for more), or a vest, would I need more pistol mags, I would need green gas until the warranty is over then a propane adaptor, or should I get a red dot sight because I can't see through my iron sights with my full face mask. Everything at the sale will be 20% off. Also I would like to have around $250 left for the psvita.