You are asking the wrong question, and most of the answers you've had so far are answering a different one.
"Cheap general vs expensive niche" assumes links are one thing you buy once. They aren't. In a niche like automotive where you're competing with sites that have tens of thousands of referring domains, you are never going to out-buy them at the top. Five expensive niche edits will not move a page that a Motor Trend article is sitting on, and 500 cheap generic links pointed straight at your money site will do nothing at best.
What actually works in that situation is picking your fights. Forget the head terms the giants own. Take the long tail pages, the specific model, the specific fault, the specific comparison, where the competition is other small sites and forum threads. Those pages need far less to move.
Then structure the links. A small number of genuinely relevant links, two or three decent placements, go to the money page. Everything else goes into a layer between you and those links, buffer properties with real content, and volume gets built at that layer, not at your site. That is what people mean by tiered link building. The cheap links have a job, it's just not the job you were about to give them.
On "does DA go up", DA is a third party score that Google does not use. It rises when you get links, but chasing the number is how people end up buying garbage. Track rankings on your actual target pages and nothing else.
And one honest caution. In a competitive niche, buying a handful of links and waiting is the slow expensive way to do nothing. Either build the structure properly or don't spend the money.
