I've never made glaze from scratch. I've always used it straight out of a tub since it's readily available at most baking supply stores. You can add different flavorings and colorings like banana essence to it if you want.
If you did wanna try making glaze from scratch, THIS SITE has some info you may find useful.
The only food store I know of near me is Sur le Table, who probably have the price really jacked up. I think I'll try some filtered banana puree, water, sugar, and unflavored gelatin. If that doesn't work I guess I'll just use banana jello. D:
I use a clear glaze for bakers. If you want, you can also use an apricot jam (try to get those without too much pulp, else you have to strain out the pulp) and heat it up with a little water to glaze your cakes and fruit.