Lee, Kodak D-76 has identical (or so they say) results to Ilford ID11. Both come in a powder form which you mix into a stock, although the Ilford comes in two packs that have to be blended in order, and the Kodak in a single packet. The Ilford can be bought in 1 litre or 5 litre forms. I like the five litre size, as once mixed, it'll last me months (if kept carefully, it will keep fresh at least six months). The Kodak, although made in Germany, comes in a packet to make either 1 litre, or a US gallon (3.8 litres). In both cases you mix the stock in hot water at the recommended temperature, but as I said, the Ilford is divided into two packets to be mixed in order.
I find that ID11/D-76 make useful fall-back developers, finer grained than Rodinal/R09. I use them one shot, either 1:1 stock to water, or if I'm feeling really mean, 1:3 stock to water. I like the ID11, because the five litre version fits nicely in a reused five litre drum, and it is made in the UK. However, the Kodak 3.8 litre works out a little cheaper. To keep the stock good, it's worth trying to squeeze as much air out of the drum as you use it, while you can. Otherwise once mixed, it'll give you months of cheap fine grain developer.