Hi. There are other suppliers however you'll be looking at an extreme uptick in expense as lab supply websites are quite pricey and shipping is generally not free. If you have a microwave or stove and a scale (I'm assuming a homebrewer would) you can macguyver a recipe together and set your own plates. This is what we do in my lab at least. Food grade agar is plenty good https://www.amazon.com/Agar-Powder-Ounces-Excellent-Strength/dp/B007PJAOG4/ref=sr_1_11?dchild=1&keywords=agar&qid=1585931801&sr=8-11. Petri dishes https://www.amazon.com/Corning-Polystyrene-Petri-Dishes-Lids/dp/B06WP182KT/ref=sr_1_10?dchild=1&keywords=petri+dishes&qid=1585932135&sr=8-10. If you were to go with fisher https://www.fishersci.com/shop/products/bd-difco-dehydrated-culture-media-potato-dextrose-agar-3/p-4901946#?keyword=potato+dextrose+agar its about $74 for just agar without shipping. Grainger is more expensive at $109 but cheaper per gram https://www.grainger.com/product/ACUMEDIA-500g-Potato-Dextrose-Agar-39M260 and also has a late arrival date. Being a lab manager the cost of quick turn around on lab supplies can make your head spin and I would highly recommend amazon just because the price to performance is phenomenal. If you have "fuck you" money to spend on supplies feel free to look at lab supply websites (SigmaAldrich, FisherScientific, VWR) Fisher is usually the cheapest their kind of like the Walmart of the research world. Some smaller companies may be competitive in pricing such as Midwest Scientific, or RPIcorp. No matter how you go about it though shipping costs will be high compared to amazon and many online retailers do not offer free shipping unless you buy hundreds of dollars worth of supplies.