Inner-city residents are making more than $3500 a year renting their parking spaces to drivers desperate to avoid rising parking fees and packed carparks.
With parking becoming scarcer during the day, CBD businesses and residents are increasingly making their unused private parking spaces available.
Rob Crocitti, who co-founded Melbourne-based booking service Parkhound this year, said there had been a big rise in demand from Perth customers.
"We've had more traffic and more inquiries," Mr Crocitti said.
"There have been big spikes in the Perth CBD, Subiaco, East Perth and Northbridge."
On Parkhound, people list their parking space or permit, and set a negotiable price for an hour, day or week's rental.
Mr Crocitti said 164 customers had registered with Parkhound in Perth since the service started, with bookings up 47 per cent in recent weeks.
He said recent cost rises, such as the $2 charge for parking at Perth train stations, might be behind the increased demand.
"One seller had six bays available on Hay Street and wasn't renting any, but all of a sudden he's rented three for around $90 per week," Mr Crocitti said.
"We've seen people make $3500 per year on a single bay. All of a sudden the rent on that inner-city pad doesn't look as expensive, because you've got someone else willing to pay 20 to 30 per cent of the costs."
Although owners are turning a profit, they are also undercutting many council and private operators. Parking spots were available for $10 a day in some areas, compared with up to $40 a day in bigger carparks.
Ron Leoncio, of Caversham, said he and his wife paid $15 a day for their bay on Murray Street.
"The cheapest carpark near here charges a flat rate of $18, so I thought we might as well look at the alternatives," Mr Leoncio said. "The owners weren't using the space, but they wanted to offer a proper service rather than putting it on Gumtree."