Skybus tickets can be bought for $33.80 return or $20.20 for a one-way via Agoda under the category of, activities (cheaper than booking direct with Skybus and it works well from my experience).
I've used this when travelling solo, but when travelling with others, Didi is a great option via T1 rideshare pickup point and may be cheaper (along with collecting some Velocity points, if linked).
As Matt Graham pointed out, watch out for unlicensed taxi drivers, who can be very pushy.
They may jump out of their cars at the T1 rideshare pickup point and attempt to convince you to quit your Uber/Didi app booking and jump in a car with them. It's quite bizarre that this still happens (I've experienced this twice in the last month alone).