Biopunk- My Question

Why aren't more affordable, do-it-yourself diagnostic tools more widely available to the public? We have all heard about pregnancy tests and even at-home drug screening tests, but why isn't there a test for cancer? Or any other disease, for that matter? It seems like some sort of DIY cancer kit could do fairly well on today's market. I suppose that mass producing such kits may prove difficult, but there could also be a way to sell the product not fully formed. The kit could come with all of the necessary components and a set of straightforward instructions, the the buyer could put the pieces together easily enough. I imagine it wouldn't be too much harder than putting together an Ikea dresser. I think such tests could prove very useful in today's world, especially with the Baby Boomer generation reaching an age where disease is a high risk. I think the Biopunk movement is taking great leaps in the direction of making science affordable and inclusive, and the next step is clearly to make it more widespread.