$1500 for a very good set up if you really want to jump in and get everything you need but $1000 will do too.
You can go cheap on SOME things but others you should spend the proper amount on.
Dont go cheap on a gun. Buying a used gun might give you problems unless you know what to look for in a used gun or are ready to give it to a gun tech to take apart and check it over and replace some parts with stronger and longer lasting ones.
Buy a decent set of goggles, those $30 goggles from canadian tire and walmart are pretty low quality that fog easy. I bought JT spectras with a dual lense for like $75 from badlandspaintball.com
Dont cheap out on your battery or battery charger, a lot of problems with both of these if you buy no-name brand ones or just plain shitty ones. A good battery and charger will last you a long time. I use a Sanyo 8.4v 2400mAh battery and TLP 4000 charger (used them since 2004-2009 and still both work just fine)
You can pick up mags on here for cheap but if your starting out I believe a highcap is suitable but you can also order them online from like RSOV.com
For camo, hit up a local army store or buy online... you dont exactly need the super 1337 issued canadian stuff nor do you have to get multicam for your first day out. Might as well just get a set of woodlands camo for like $25 each the pants and shirt.
You can buy used canadian boots for cheap at any surplus store or even online. If you have steel toed boots, I dont reccomend wearing them to the field as they are not as comfy as actual military boots made for running.
Get a vest if you like, you can buy them online for cheap if you dont care if its a copy of a popular vest ( ebaybanned.com ) or you can buy a nice MOLLE vest and get a couple pouches for your mag('s) bb's and whatever else you need.
Personally I started with roughly $900 of a budget, but I already had camo and a SAAV vest. The $900 was spent on a TM ak-47, 1 highcap mag, 8.4v Sanyo battery, TLP charger, bag of bb's... I also bought used army boots for $40 and a paid of goggles (JT spectras) but now guns are more expensive than when I started and TM aeg's went for like $400-$450...
"I feel no emotion, just recoil."