I'm genuinely sorry for your losses. I've been pregnant several more times than I have children to show for it and also have personal experiences of pregnancy tests. In my case, the cheap tests showed positive when the expensive tests didn't and this was because the expensive ones weren't as sensitive. That's just the way they work.
My anecdotal experience is just that though. The fact remains that spending a lot of money on a test does not a better test make. Realistically, all home pregnancy tests are pretty amazing if you think about it. But if somebody is wanting to test, it's important that they know they don't need to spend £13. That's a lot of money and my sole concern always remains that vulnerable, hopeful, desperate women aren't hoodwinked into spending money they don't have because of clever marketing.
Pregnant women and mothers are always targeted by marketing and convinced they need to spend a fortune from tests to formula to nursery decorations. The marketing works, of course it does. But it is bloody annoying.