it really is getting cheaper and cheaper to get into the game; it's just most of the die-hards will try to scare you off with the prices of mil-sim kits. You can be playing in a game with a $200-$250 AEG that might last you one season, or ten. The krakens, the new SIG55x's - they're cheap, and you get what you pay for; the kraken might literally break in your first day, or run for 3 years.
The rest of your gear, minus solid goggles (many places won't let you play without quality eye wear like JT) can basically consist of a hoodie and jeans.
Like I said - the die-hard mil-sim crowd are going to shit on this reply, because it's ruining the integrity of their game!!!!!
And yet there's still plenty of games for them...
So yeah, if you can budget $500, you can start playing and learning the game and you can upgrade later should you choose to.