In Dunedin, The Perc Cafe owner Sarah Hussey had 20 tests arrive yesterday, costing $289, well above retail value.
Hussey had two staff down with Covid-19 and she said staffing her businesses was a juggling act.
"I feel like we're just scraping through," she said.
Countdown head pharmacist Jeremy Armes said customers would "start to see" Rats this week at $32.99 for a five-pack.
"We'd encourage customers to only buy what they need and to not stockpile these tests," he said. "People can still head to their local testing centre or GP for a free rapid antigen test if they are symptomatic or a household contact of someone with Covid-19."
The Te Kaika testing centre in Dunedin had been going through hundreds of Rats a day.
Medical practices in the South were to each receive a supply of at least 245 tests, it is understood.
Foodstuffs could have Rats in its supermarkets "as early as next week" and a five-pack would be $32.99 there, too.
Online sales were to start at The Warehouse yesterday and they would be in store nationwide "by next week".
Rats from the Ministry of Health's central supply are not available for public sale.
Under the public health response, pharmacies are supplied with some Rats for testing asymptomatic unvaccinated people who need a negative test for travel or to attend court.
Urgent Pharmacy in Filleul St, Dunedin, had a supply trickling in, but this was for critical workers and other people who met limited criteria.
The Government has orders for 180 million Rats in the next six months.
