Contrary to what many people think, building any site on what you like and your interests is not a very good idea. It’s not going to be very profitable. I still can’t figure out why people want to build niche sites based on personal interests. I guess it could get me started with learning Internet basics, but it wasn’t going to build a cash flow. I found out very quickly that there were more profitable markets to build my sites around. Make sure you provide the niche that people want.
Don’t create a product then find the niche, you need to do the opposite, find the niche then supply the product. You need to remember that just because a certain phrase pays well, doesn’t mean you will get a good search engine ranking for it, or that people will be attracted to your page. Should you go after high paying phrases regardless of topic? Just remember not to jump on the phrase bandwagon unless it’s related to your website. Also, make sure it’s something you have a passion for.