Pavers for $40-45 - are going to be pretty unattractive grey concrete (well, cement) ones, right?

Even Bunnings (albeit marketplace) has 100mm geogrid for $20 / square metre.

Most local vendors have 'call us for pricing', but I've found a few others in the $10-20 range. Obviously, yes, in-fill on top of that - say $250 a cube depending on your tastes, so add $12-25 per square metre.

As per sibling comment - with some fabric underneath, and a modest amount of ground prep, installation of this stuff sounds fast and easy.