I have no idea how expensive they are, but I've occasionally considered a precast concrete plunge pool:

[https://www.houzz.com.au/magazine/dive-deep-11-reasons-to-buy-a-plunge-pool-stsetivw-vs~26038438[(https://www.houzz.com.au/magazine/dive-deep-11-reasons-to-buy-a-plunge-pool-stsetivw-vs~26038438)

[https://www.houzz.com.au/photos/monroe-street-house-modern-exterior-austin-phvw-vp~741524[(https://www.houzz.com.au/photos/monroe-street-house-modern-exterior-austin-phvw-vp~741524)

http://www.allcastprecast.com.au/products/plunge-pools

Hi Trudy,

For a small footprint like 5x2m or 3x3m, a few cheaper alternatives to a full custom concrete pool build worth looking into:

Plunge pools (precast/fibreglass) — for that size, a precast fibreglass plunge pool can often come in well under $25k installed, especially if access to the backyard is reasonable and there's no major excavation drama (rock, tight crane access, etc). Way less labour than a fully custom concrete pour.

Above-ground or partially recessed pools — if you're open to it, a well-built above-ground or semi-inground pool with good decking/cladding around it can look genuinely nice these days, not like the old-school backyard kit pools. Worth considering if budget is really tight, since you skip a lot of the excavation and shoring cost.

Plunge pool + spillover or splash deck — rather than a "proper" lap-style pool, a small plunge/cooling pool with a timber deck surround can still feel like a real feature without the size (and cost) of a bigger pool.

A few cost drivers to watch regardless of which way you go: site access (can a small excavator/crane get in, or is it a hand-dig job?), ground conditions (rock = $$$), and whether you're doing concrete/tiled vs fibreglass shell (fibreglass is usually cheaper for small sizes).

Might be worth getting 2-3 quotes from smaller specialist plunge pool builders rather than the big pool companies — they tend to be more competitive at this scale. Happy to share more thoughts if you post some backyard photos/dimensions — I do work in the space (small-space renovations) so I've seen a few of these come together.