Found these while shopping for some new blinds, appears all sizes within each category are priced the same no matter what you select. Just collected our c&c order before posting as it felt too cheap and a pricing error I thought they'd cancel.
Roller blinds come in ice or slate and cost $20 for all sizes
90x210
120x120
150x210
180x210
Ice: https://millers.co.nz/collections/ready-made-blinds/products…
Slate: https://millers.co.nz/collections/ready-made-blinds/products…
Venetian blinds are these sizes:
60x137
90x137
120x137
180x137
White birch $30
https://millers.co.nz/collections/ready-made-blinds/products…
Black $40
https://millers.co.nz/collections/ready-made-blinds/products…
Teak $40
https://millers.co.nz/collections/ready-made-blinds/products…
Delivery seems to vary by location, greater Christchurch was $10 but looks like Auckland would be $20.
The roller blinds in particular can probably be trimmed down to fit smaller window widths.