The most popular plan is the 100GB for $150/year which comes to $1.50/GB/year. It costs around $0.18/GB to transmit and receive in BW costs based upon various datacenter estimates YMMV. The max, 250GB is $1/GB. Thus, a 1T storage requirement would probably be maybe $500/year? That’s just for storage.
Assuming a roundtrip for all data, bandwidth costs can approach $0.35/GB or close to 35% of the yearly cost for the 250G plan and %70 of the yearly cost on my mythical 1T plan.