A PS3 or 360 is significantly cheaper than buying a next gen console or gaming PC though...
If you already have a gaming PC, PS3/360 offer a vast library of games, something PS4 and Xbox One does not at the moment (so good luck if you want to play something else than Ryze and Forza 5, or Killzone Shadow's fall and Knack)
If you buy the 12GB PS3, be prepared to buy a larger HDD down the line (unlike the 360 you can use an off-the-shelf 2.5 inch drive) as the internal storage won't last long.
If you already have a PS3/360 but not a gaming PC, do consider one, the entry cost is higher but there's already a huge established library and frequent discounts.
Well unfortunately there's not enough next gen consoles for everyone. Plus they are expensive with hardly any games. I have PS4 and Kill-zone (as Knack was rubbish) and all the other stuff I have on a PC which cost me a third of the price. On The X-Box One I have Forza, Ryse & Dead Rising 3 (Enjoying Fifa and Basketball as well - but you can get these on current gen) and then rest on PC. So I'd wished I'd waited till next year for next gen as nothing out at mo worth buying them for. The PS3 has some great games and If a Parent buys one of these and a PSN year sub (for all the free games, the kids are going to be happy) Plus a vita and some great games like last of us uncharted etc, then you can get a lot more for your money compared to PS4. Also 360 Good (I have fallen out with mine as 320GB hd is full and you can't upgrade it - so MS needs to let people put a 1TB hd in it like Sony do the PS3 - none of this uninstall games, if you have a collection you want it all on your machine). Also a cheap steam PC may be another option for the kids (My steam PC has a 4TB and is nearly full, but I can just buy another 4TB without issues unlike consoles - So this makes the new consoles not so next gen, as 500GB hd these days is poor - 1TB - 2TB would have been more next gen.).
I work with some people at work and they have bought there kids a PC and they are not bothered about consoles any more because they can afford so much more with there pocket money and don't have to pay for live etc to talk to their friends online.