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These mower blades are $22 in store at Bunnings, however, they are $12 online.
The packaging says they should fit 18" Victa mulch-n-catch mowers from 1982-2013.
They honoured the price in store after I pointed this out.
Victa 18" Mower Swing Blade $12 + Delivery ($0 C&C) @ Bunnings Online
50
This is part of Black Friday / Cyber Monday deals for 2021
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Bunnings prices for mower stuff are ridiculous now. I used to buy a Briggs & Stratton Quantum engine air filter (square paper type with blue rubber edge) and a pre-filter cheaper than anywhere else. Then they didn't have them for months. Now the air filter is back but it's more expensive than everywhere else and they don't even stock the pre-filter.
Try your local mower repair store first. Not only were their blades already cheaper than this again, but I also asked for and received a discount if I bought 10x or more pairs. There seems to be cheaper ones on ebay than this too, but I have no idea what their quality is like.
Note: Never buy the absolute garbage brand SCA sells. Several times I used their new blades the bent edge was completely gone after mowing over a rocky area of my lawn just once, or twice at the most.