Class is gonna matter somewhat regardless of which flash cart you get at this point due to wanting the real time guide option. It isn't really important though. I'll touch on that a little further down.
I would suggest the Supercard DSTwo. It comes with the features you want with lots of nice extras. It runs about $35 from most places.
Check out the features here:
http://eng.supercard.sc/manual/dstwo/
Check out the GBAtemp review here:
http://gbatemp.net/t232281-supercard-dstwo-review
For the MicroSD card, I would suggest about an 8gb Class 4 Sandisk. The Class 4 is to guarantee everything works as it should, though you can always go to Class 6 if you want to be really safe. Pretty sure upwards of a Class 6 is unnecessary though...