Depends how closely related your site is to the content from the “busy” site.
Also, I personally wouldn’t put all of my eggs in the same basket, especially if that 3k is your savings. This is just my opinion but I would invest 500$, see if I have results and reinvest my profit instead of going all-in on that one site. Either way, it will still be there in a few months and you can pay the 3k then. As I said, that’s just my opinion. Others may suggest you to risk everything you have, I just prefer the incremental approach.