+1 for fogtech. its a great product, its the only thing i'll use for anti-fog and ive even turned a few others onto it.
as for eyewear your face should determine what kind of eyewear you buy. always buy ansi or csa rated safty glasses. the price tag of them does NOT matter but how they fit does. if you have a weird shapped face you may need fully sealed glasses. if interested in full seal goggles there are a few models with built in fans to help fight fog, the cheap ones work but the fan is apparently very loud. also there is nothing wrong with using a paintball mask if thats your preference. however most people say its harder to aim down sights with a paintball mask so some modification may be required to properly aim down sights
i have bought 3 different glasses so far. i started with standard safety glasses *$10* which were ok but didn't fit super well, then last year i bought a set of ESS Ices *$65* which fit better on my face. they also came with a hard case, 3 lens' and IMO very importantly a retention strap. this winter i bought a set of smith optics *$104* which fit even nicer on my face. the smiths also come with a hardcase 3 lens' and a retention strap. i bought mine with multicam frame, which made it 10$ more.
this year our team implimented some new rules, one of which is eyewear retention straps. this is because we can see a hazard of running while being shot and your glasses falling off by accident...its a rare occurance but we'd rather not see anyone go blind