I was looking online for seabird guano as well. DTE is a 5lb box 0-11-0 ($22-24)
Roots Organics is a 3lb bag 0-12-0 @ ($14). I went with the Roots Organics because it was cheaper & has 20% calcium added. Not sure about FoxFarms Happy Frog.
I use Down to Earth for Greensand & Azomite. DTE is a good brand, I also use various TPS, BioAg, Microlife,RAW, Roots Organics & Dr. Earth products as well & love how much I get for the money (good value). Plus I got that free bunny honey from owning a rabbit, also have a bag of 90% fulvic acid & a bag of chitosan oligosaccharide & some Blackstrap molasses. Recharge & Plant Success Organics for PGRP.. bases are covered lol. Always stay making teas