I've told you where it comes from, the oil from here. Now the practical part: where you buy it, the genuinely good one.
First rule: not at the supermarket. Real taggiasca oil you get at the mill, from the producer, and almost always by the tin: a three or five-litre can that lasts the year and costs less, at equal quality, than many shelf bottles. Taggiasca gives a delicate oil, low in bitterness, fragrant; if you want a guarantee, go for the DOP «Riviera Ligure».
The family mills, in the valleys behind Imperia, are the right place. Many open their doors, let you taste and sell direct: you'll find them below, from Dolcedo to the Argentina valley.
Then there's the special case: Fratelli Carli, in Oneglia. It's Imperia's «commercial» oil, the one you find all over Italy, but at the Emporium (with the Olive Tree Museum next door) you buy oil, preserves, pesto and gift boxes too. Convenient, reliable, and part of this town's history.
The local's advice? For everyday cooking, a tin from the mill. For a gift, or to try without fuss, the Carli Emporium. Either way, it's the oil that makes the pesto, the farinata and the frittata.