R.J.
My son started saving for his laptop when he was 5. He was very, very adamant about wanting a MacBook (his K class had Macs, and I have a MacBookPro). Okay, kiddo, house rules: You save up half and pay for ongoing charges (or part of them, at any rate... for example he pays $10 a month for his phone line which is what it costs us to add a line), and we'll match the half you save.
It took him 3 years. It didn't NEED to take him that long. He got $5-$10 dollars a week in allowance. If he earned his full allowance AND didn't spend any of it he could have had it in a year. BUT he has his expenses (like his phone line), and any purchases he chooses to make (games, strawberry & creme drinks, birthday gifts, going dutch, etc.) and his pet charity (he has a thing about summer kids lunch program he gives $50-$100 to every year), and he has had weeks where he only earns part of his allowance or none at all.
He had the money for half just after his 8th bday. We matched it. And he has owned his own laptop for just about a year now.
In the intervening years he's used an old hand-me-down-dinosaur-dell laptop (free) and the desktop.
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I don't think there's a blanket "right" age for things. I think it's a family by family decision. I have friends in the country who will drop 2k on a pony for a 5yo, but not even let their 5yo use the house desktop computer much less buy one or have their own, even if it's free. Is a pony the right decision for ALL families? Heck no. Neither is a computer. Family by family choices. Our son has had access to our desktop since he was 2 and a half. He wanted his own laptop since he was 5, he saved for (half of) it. Some parents will be aghast we agreed, others will be aghast that we didn't buy it ourselves for him. Whatever :) Different families, different wants & needs & priorities.
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People often gripe "What will they want next???" Well. My son has had a camera since he was a toddler, ditto a hand-me-down laptop, a phone, and an iPod all from 5 and under (all costing $0/free - $50, btw., I've spent more on legos). What has he ASKED for in the past few years since for bdays & xmases? Squirt guns. Legos. A paddle ball (yeah, the 99 cent type), a $10 game.