Your usage appears similar to mine, about 250g per week.
So Id say you just have to decide how often you can purchase.
Im quite happy at the moment to purchase weekly or fortnightly.
If I buy per fortnight I get some roasted that day or so and some a little older to use straight away.
No need for the freezer. Just store somwhere dark and cool.
Freezing could lead to dampness upon thawing.
I havent tried DiBartolis yet.
Coffee Alchemy has been good for me.