Pakse is cheap to be in and cheap to eat in; the scooter, the fuel and the nights on the plateau are what your money actually goes on, and how many loop days you do is the whole budget question.
What a day costs
Pho at Lankham is 20,000–25,000 kip, a plate of fried noodles about 20,000, a made-to-order sandwich 28,000, a plate of pasta 35,000 and a whole grilled fish 60,000. Staying in the centre and day-tripping, 200,000–250,000 kip a day is comfortable.
Bike hire: read the deposit terms first
Loop rentals are cheap by the day, but the money is in the deposit and the damage clause. Photograph the bike from every angle before you ride off, agree what happens if it breaks down on the plateau, and pay for an extra day rather than riding back tired in the dark.
Base in Pakse and day-trip the rest
Wat Phou is 45km south and the big waterfalls are around an hour east, so a cheap central room plus day runs beats paying for beds in three towns. The exception is the loop itself, which only works if you sleep up on the plateau.
The overnight bus saves you a bed
Sleepers from Vientiane leave in the evening and reach Pakse around 6am for roughly ten hours on the road — the railway does not run south of Vientiane, so it is this or the Lao Airlines flight. Take a fleece; the air conditioning is merciless.
Cheap hours while you wait for a bus
The Champasak Historical Heritage Museum is small and quick — Tham-script stelae, old pottery, a model of Wat Phou, ethnic textiles upstairs — and the Sedone-Mekong junction at sunset costs nothing at all. Together they fill an afternoon between departures.