The clean comparison formula
Total ownership cost = hardware + activation + recurring subscription + optional protection/replacement fees. Divide by months owned if you want an effective monthly cost.
Do not compare monthly headline rates across different billing terms
A five-year prepaid plan, annual plan and month-to-month membership are different commitments. Long prepaid terms can lower the effective monthly rate but increase switching cost if the service no longer fits your needs.
Battery can have an indirect subscription value
Fi Series 3+ publishes much longer battery life in home-heavy use than Tractive DOG 6. That does not change the subscription invoice, but charging friction affects whether the owner actually keeps the tracker on the dog consistently.
Coverage is more important than a small price difference
A cheaper membership is not a bargain if cellular coverage is weak where the dog actually roams. Check the current network and regional support before committing to a long prepaid term.
Use the pet GPS subscription-cost calculator.