I so encourage you to stick with a narrow site concept. It is good to have "your corner" of a niche. Once you have cornered your corner, it's likely you can grow your site in the same niche. In the meantime, you'll have more success on which to build.
Some of my best sellers are products with single digit numbers in BrainstormIt.
Do remember that the Site Concept Home page keyword will need the sort of Supply numbers you are showing, and that the T2 and T3 keywords will have different number requirements.
I hope this helps.
[Edited to note:
Your homepage goes to index.html and the .com. Sitesell had made a change made years ago and I cannot remember when that was; yet it makes a difference somehow, especially having mixed internal links to your home page. Perhaps you could write to Support and/or search for the old thread on this issue. I've searched and found this item, yet it is not descriptive of the change or the time: https://forums.sitesell.com/viewtopic.php?p=1384675#p1384675