Tried using the homemade medium today.
I used a blender to chop the potatoes cuase I have no grater. Worked well. The smell of cooking potato and its skin is interesting. I ended up burning alot of the stuff at the bottom of the pot.
Also, either I didn't boil it enough, or 5 grams of Agar just isn't enough. Tomorrow I will attempt to boil off any extra water and add 5 more grams of agar unless someone thinks its a bad idea.

In anycase, here is some of what I did:
I cooked the potato and banana and honey water till it was boiling, then added the agar, then boiled it again. Finally I filled jars and sterilzed the stuff in an autoclave. But then I found out that the stuff wasnt hardening even in the fridge. So, tomorrow I will boil some more water off and add some more agar.