So you want to start, let's say a fishing site, but have a gardening domain? Doesn't sound like a good idea.
Unless you can work it out to be something like flyfishingwith.yourgardenhos(e).com, that would be awesome.
It's honestly not that expensive to create a niche website. You could use the 0.99 .com domain coupons to get your own domain and there are many free hosting giveaways on bhw to help you out. Content wise you could probably write it on your own if your english is decent. The total cost of it would only be $0.99.