House price sense check

We've been looking at this property https://www.rightmove.co.uk/properties/158198156 .

ES told me it's been on the market for about three weeks, and Rightmove says it's already had a price reduction.
There's no chain, and the seller is keen for a quick sale. The asking price is over £450k, but according to HouseMetric https://housemetric.co.uk/results?str_input=Sm6+7dq+ , property prices in that area range from £4,750 to £5,880 per square metre.

I know that square metre pricing can be a bit all over the place in the UK, but still that would put this house (which is roughly 78 square metres) towards the high end of the bracket, which I don't think is justified. There are plenty of new builds nearby that are more in line with that pricing. Also, the house needs a brand-new boiler. The main bedroom is a decent size, but the other two are tiny, really only suitable for a single bed at most.

Are the sellers being a bit ambitious with the price? What would be a sensible offer? We really liked the property and love the area, so we're keen to make an offer, but we think £450k might be a bit steep (though happy to be proven wrong!). Cheers!