There are several suppliers of ready mix fuel in the US. By the time you get the ether and igintion promoter I think it is cheaper to use ready mix rather than mix your own.
I use Davis Diesel Power, but I have not bought any for a long time. If you are just going to use a little bit, buy the smallest containers available as you lose some ether every time you open the can. I have built and run six small engines fairly recently and have only used about a half of a quart can.
I have not looked lately, but I did see Tower Hobbies has the Davis in gallons for about $30 plus shipping. It doesent look like they selling the quart cans. I think I got mine from the Dr. Diesel website. Of course, you can always buy a gallon and then pour it up into smaller containers. If you do, use metal containers with good sealing lids.