I'm T2 so self-funded meter and strips wise.
Initially when I started low carbing, I used Ketostix to test urine but I found they barely gave me any clear results which I discovered was due to them measuring waste ketones, and I was already in ketosis and burning them up as fuel rather than weeing them out.
After that I discovered and bought a basic Ketonix breathalyser which gives colour coded "traffic light" ketone levels. It was a high initial but a one-off expense . There was also a more expensive/complicated model which did give numerical results, but I think it needs a computer for this. Some cheaper alcohol breathalysers will work for ketones as they apparently both measure breath acetone , so they may be a reasonable and cheap and accurate way of testing. But I believe there are also cheapish ketone breathalysers available too on Amazon UK now , so maybe worth a look as again they would be a one-off cost.
I also used the original Libre 1 sensors for a while, and my initial purchase package came with a reader which would also act as both a ketone and glucose meter. This all was self-funded. and ketone strips can be costly, but I like it as it's been a handy 3-in-1 gadget!
And finally{ cheapest of all if you're lucky: it's sometimes possible to taste or smell "ketone breath" - I've experienced this a few times but not enough to be a regular measure!