Pretty straight forward site, although a bit bland. It could use some color (besides the ad’s). I would add an image in the header as a starting point. And you definitely need an introduction on the home page. Give a short description of what the site’s purpose is.
Unless Amazon is paying for the ad, I would move it below the content. Or maybe you could have a Links page with sources of Uke’s, music, etc. The B&H Photo image could be smaller too, it’s pretty imposing as it is. I think the two ad’s overpower the rest of the content. Not because they are ad’s, but because they are the only things with color. Reduce their impact and put more emphasis on the purpose of the site.
Good luck,
Nick