So, I went to the cashout page and this is what the breakdown of the one year unlimited plan comes out to be ...
So, this is the answer to the question "How much does Mint Mobile's 'Unlimited Plan' cost per year?" ...
(Please note that this is for the state of Florida; other states may vary, however, should be close)

Renew Unlimited Data Plan for 12 Months

Summary
Unlimited - Recharge Data 12 Months
$360.00
----
Recovery Fee
$25.25
----
Taxes & Surcharges
TOTAL - $4.41
--
FEDERAL UNIVERSAL SERVICE FUND
$2.14
FEDERAL COST RECOVERY FEE
$0.05
FEDERAL COST RECOVERY CHARGE
$0.08
STATE SALES TAX
$1.38
FL PREPAID WIRELESS E911 FEE
$0.40
COUNTY SALES TAX
$0.23
FL COMMUNICATIONS SERVICES TAX
$0.10
LOCAL COMMUNICATIONS SVC. TAX
$0.03
----
Final Total
$360.00
$25.25
$4.41
-------
$389.66 ($32.47/Per Month Total)

So, I went to the cashout page and this is what the breakdown of the one year unlimited plan comes out to be ...
So, this is the answer to the question "How much does Mint Mobile's 'Unlimited Plan' cost per year?" ...
(Please note that this is for the state of Florida; other states may vary, however, should be close)

Renew Unlimited Data Plan for 12 Months

Summary
Unlimited - Recharge Data 12 Months
$360.00
----
Recovery Fee
$25.25
----
Taxes & Surcharges
TOTAL - $4.41
--
FEDERAL UNIVERSAL SERVICE FUND
$2.14
FEDERAL COST RECOVERY FEE
$0.05
FEDERAL COST RECOVERY CHARGE
$0.08
STATE SALES TAX
$1.38
FL PREPAID WIRELESS E911 FEE
$0.40
COUNTY SALES TAX
$0.23
FL COMMUNICATIONS SERVICES TAX
$0.10
LOCAL COMMUNICATIONS SVC. TAX
$0.03
----
Final Total
$360.00
$25.25
$4.41
-------
$389.66 ($32.47/Per Month Total)