I haven't checked lately--is their P/E still at infinity? Ultimately Amazon is a retailer, and yes their brand name is huge right now, but I never liked investing in retailers. I've seen what happened to the vast majority of them over the years. Customers' tastes change, and often another store comes along that people flock to. Most of the department stores from my childhood alone are dead.
Amazon has always had tremendous revenue, but it's never been very profitable. They've been in startup mode for years now, spending money to acquire customers, but rarely actually making money. So no, I would not invest in their stock. Short-term you might make a profit, but I don't think it's a long-term play.
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It's not complicated at all if you just want to buy stock. You have to find a brokerage, and there are tons of them online (don't know about your particular country). Some have minimum amounts to start an account. You can buy one share of Amazon, that's the minimum, and you have to pay a commission that varies between brokers. I pay something like $8/trade with my broker.