The building, known as "The Ministry of Works", that houses The Cheep Shop officially changed hands at the end of April.
"The new owners wanted us to squash into the back half of our shop, with a new business taking over the front of it. It just wasn't going to work," Morton said.
"It's an opportune time for us to leave, really."
One of the building's owners, Shane Hobson, said The Cheep Shop's rent of $115 a week for 240 square metres wasn't sustainable to deliver the maintenance they were committed to.
There were three roof leaks that needed to be fixed.
No notice had been served.
"It's a colossal amount of space," Hobson said.
"We were trying really hard to keep them [The Cheep Shop] there because I absolutely don't want to be the landlord who buys a building and kicks everyone out.
"We offered to keep the rent the same if they condensed themselves into half the tenancy, so that we had room to put another tenant in. They have elected not to continue."
Bird Rescue Whanganui Manawatū would continue and Morton said she was already thinking of other ways to fundraise.
There was still a core group of people who donated regularly.
"It's sad to see the end of The Cheep Shop because it's been a part of us for so long.
"We would like to thank Fee [Fiona] and Ant for all they have done and sincerely appreciate all their hard work in running the store."
In a joint statement, Barlow and Dingle said they thanked all their regular visitors, donors and customers.
"In particular, Ant's colleagues at the [Whanganui] DHB for their wonderful contributions over the last few months, Riverview 4Square for their cheese platter, Graham for his weekly contributions and Waverley Bird Rescue for their donations."
The last opening days will Saturday, June 18, from 10am to 4pm and Sunday, June 19, from 10am to 2pm.
"There will be a massive sale to get rid of stock and lots of freebies to be had.
"Even our shelves and display counters must go. Leftover stock will be donated to other charities."
