I'll try to be as concise as possible in answering your questions.
There is no direct government appointed age to participate in any airsoft game, their maybe rules and regulations in regards to participation by the owner of the field but at this time no legitimate laws exists to my knowledge. Due to the nature of airsoft it is maintained through out this community that purchasing and ownership of airsoft should only be available to those who are the age of majority. That way if any incidents where to occur, the only person responsible would be held accountable instead of a guardian. There are locations through out Canada that cater to all ages, some facilities and groups allow people as young as 16 and I believe even under 16 in one specific place that I cannot remember at this time. Although the majority of the time participation age is set by the host of the game.
Game venues exist through out Canada and prices vary from region to region.
It has been debated and established that an entry level contribution between four to five hundred dollars would be sufficient to begin. This price would only cover the extreme basics and in some cases may not be enough to cover the basics depending on your choices.
"Its only a little bit on fire"