Got tired of buying the stuff since the majority of it ends up in in squirrel bellies, so I started making my own about 5 years ago. Here's my recipe (makes 4 4"x5" blocks):

1 lb lard
1 scoop peanut butter (chunky)
2 cups rolled oats
2 cups corn meal
1 cup flour
1 cup bird seed

Melt lard/peanut butter (microwave 3 min), mix in the rest, pour it out in a flat container about 1" deep and put it in the freezer. Once it's solid you can put it out for the critters or wrap it up for later use. I've "borrowed" some 5"x9" plastic tubs from my wife that are perfect; pop out the frozen suet, cut in half (width-wise) and they fit perfectly in the suet cage I have set out.

A flicker (yellow-shafted) showed up at the suet feeder this morning - first of the year (seen) and fourth different woodpecker this week, adding to the Downy, Red-belly and Sapsucker. Jays, starlings, crows, sparrows, even a very confused yellow-rumped warbler seem to like it.

Regards,
Scott