I order 1000 at a time from
http://www.Reptilefood.com (I have been really happy with them you get 1000 for $10.00 + shipping) and as you know I only have Kitty.
I find if you keep them cooler (65 - 70 degrees) and feed them oatmeal and romaine lettuce they last at least a couple months.
If they are warmer they grow faster.
Of course I put a few in the gutload box every night for the next days breakfast. They really eat that gutload too, after only having lettuce and rolled oats.
You will have some die off over the two month period but not many and I figure $8 a month (I think I paid $16 - something with shipping) is not a bad budget for crickets.
-Brad