Holidaymakers face a minefield of costly and fake Covid tests when travelling overseas, as they have to navigate through hundreds of different options.
It's a daunting task - so we've broken down the cheapest options, as well as how to spot a scam.
The first thing to do is work out exactly what tests you need to take.
There are two sorts of tests to think about: those taken before leaving England, and those taken when returning.
This varies hugely depending on whether you're going to a red, amber or green list country. Any testing or quarantining depends on this.
For example, if you want to travel to England from a red list country, you have to take a Covid test and book a quarantine hotel when you return, including two more tests - though children under 10 don't need to take the first test.
You will also need to fill out a passenger locator form on a government website.
Most countries will accept a negative PCR test before letting you in, but some will accept lateral flow tests - which are cheaper.
We say 'cheaper', not 'free', because you can't use NHS tests - so will have to pay for them yourself using a private company.
PCR tests normally cost between £50 and £250 each, and give results on the same day or within three days. You can do these at home and post them to a clinic, or go to a clinic and rely on a specialist.
Lateral flow tests tend to cost £40 or less, and give results within 20 minutes.
So check the rules for the place you're planning to visit, as well as what you need to do when you return.
You can do that on a government website that is constantly updated.
Some destinations demand you take a specific Covid test within 72 or 48 hours before you go, and then present it in a certain way - such as on paper or digitally.
The government has two lists of test providers, one if you're leaving the country and one if you're returning.
But it is quick to wash its hands of any liability for bad ones.
A disclaimer above the list says: "The government does not endorse or recommend any specific test provider - you should do your own research about them and their terms and conditions."
How to get cheap tests
Fortunately, if you have booked a trip with an airline, holiday firm or tour operator you may be able to get cheap tests through them as part of the deal - so check with your provider.
For instance, if you have bought a holiday through Tui its testing kits cost from £20 per person if you're visiting a green list country.
For that price you get a lateral flow test to take before you go and a PCR test for when you're back.
For £60 you also get an extra PCR test before you go.
That's quite a good deal. If you go to Boots, for example, one PCR test would cost you £85 if done in-store or £65 for a home test kit.
Going to a private clinic can cost £200 per PCR test, according to consumer group Which?.
How to spot a scam PCR test
Sadly there are scammers out there selling fake Covid tests and all-clear certificates.
Some pretend to be legitimate companies to lure in unsuspecting travellers.
But some openly advertise they are selling fake goods and rely on customers either not being able to afford real tests or not wanting to take one - for example because they know they have Covid and want to travel anyway.
Warwickshire County Council recently spotted a case where a local paid more than £100 for a test, which came back negative.
However, the man had paid the cash to scammers, who had never done a test at all.
Many fraudsters operate on social media, and if they have websites at all these often look low-quality.
To stay safe, check that a test provider is on the government approved list.
Alternatively, a private website called Covid Testing Network lists trusted test providers. It was set up by travel and healthcare professionals.
However, you should still do research online before giving a test provider any of your cash.
If it has bad reviews, or you can't find anything about it, it may be a scam.