Are you planning to buy or maybe already bought something you were thinking about but weren't so sure about, maybe a new (used) car, a new laptop, lens, holiday package jewellery, even expensive painting?! Euros, Dollars?
I don't want to discuss brexit itself here, good or bad; only that is now seems likely and that likely means pound will go down.. maybe a lot and losing money is certainly undesirable.
Brexit does not mean the price tag of second-hand used cars, laptops, lenses, etc., will go up if it was already imported into the UK long before Brexit.
The costs of brand new things would go up after a no-deal or crappy-deal Brexit, in order to pay for import taxes, tariffs, etc.,
For example: Customers would have to pay extra for a brand new Lecia camera, the extra money will be used by the distributors to pay for the import tariffs, after all, Lecia is from Germany.
I can't afford a brand new Nikon D500 or D5, let alone a brand new Leica M9!! I'm thinking of upgrading my camera to a second-hand used Nikon D300 or D700, which would have already been imported years ago (those were made about 2007-2014). So it would hardly make a different if I buy it before or after Brexit. If the price tag for a second-hand D300 goes up due to Brexit, I would challenge the shop, ask them to prove it to me that they recently imported the second-hand D300. I'm not paying a higher price tag for something that had already been imported long before Brexit. I'm not paying extra which would cover the import costs for someone else's brand new Leica camera that had been imported after Brexit.
I'm most likely to be buying second-hand used lenses, laptops, any other equipment, stuff all already imported long before Brexit. I expect that the costs for those should not be pushed up to cover for import costs on brand new things.
I've been toying with the idea of booking a holiday to Hawaii, and I would assume the price tag makes no different, after all Hawaii is not in the EU. But if I was thinking of going on holiday to Germany, I would likely to want to go before Brexit.