For about $400 you will get about a mid range laptop.
If you want it slightly more for casual gaming, go for a mobile Ati a 10 Cpu/Apu
It should play mine craft with decent frames per second.
Mine craft is more cpu based. but I was thinking in favor of games that need a bit of help from a half decent Cpu/ apu solution also.
Intel I3 to an I5 with about 4Gb of system memory minimum 8Gb would be better though.
And again should run Mine craft ok.
But a Ati Cpu/Apu will fair better with multiple games that require a bit of graphics horse power, as the Intel graphics solution on a I5 is weaker than any Ati based solution in my mind.