Going on extended vacation to USA next year. Currently have a Samsung S5  - bought through Harvey Normans on a Telecom account so assuming its locked to them.

Keen to use it in states next year for a variety of things - browsing,  GPS Map directions, emailing and calling taxis / hotels etc.  While appreciating it may well work without me doing anything I'm wondering if the cost would work out to be more expensive than doing the following.

Therefore thinking of 

1. Unlocking it here

2. Purchasing a SIM in the USA and loading it up with an AT&T tourist card SIM etc ?

Just perused the Telecom site and it appears I can get a decent amount of data and calls /texts for around $50. The issues is my current SIM card is employer provided - it's my phone but their SIM. I'm assuming I'm going to have to purchase a new SIM anyway if I take my phone overseas as they won't change the corporate mobile plans etc

Anyone done the above - either/ or and any tips.

Thanks