Cheapest one available for 1.2G with a few minutes for calls at VTD90K-100K is not available anymore. The best rate available upon my arrival on 29September2016 was VTD150K for 3G internet with unlimited usage but no calls.
Taxi
Taxi ranges from VTD220K onwards for vouchers from the airport to District1. Research previously showed that it's supposed to cost only VTD100K. I believe this price might be possible if one walks across the airport to the main road and hail down a cab. Definitely not in the mood with our luggages so have to swallow the heftier price tag for cabs.
Visa on Arrival
Unless you from ASEAN countries, then queue on the left upon arrival at the visa counter. USD20 have to be prepared for the individual visa if I am not mistaken.