A Toy Garden has Stockmar crayons (both block and stick) on sale now ($12.95 for 8 and $22.95 for 16). Three Sisters is slightly cheaper at $11.25 for 8 (either block or stick). Hip Mountain Mama
is also similar in price.
Stockmar Modeling Beeswax - Down to Earth Toys has 6 sheets for $12.99. Three Sisters also has a decent price, but they're out of stock (they've said they'll be restocking soon). Hip Mountain Mama
is along that same price range at $13.99 for 6. A Toy Garden has a 15 piece for $23.95.
When figuring cheapest price it probably also pays to load some of these things up into a shopping cart and find out what the shipping will be. I've found in some cases that it varies widely and sometimes has made a big difference in price between the two. I vaguely recall seeing Hip Mountain Mama in one of the banner ads on MDC. If you could click on one of those it'd be even better. Some of the retailers I listed above are also listed on Mothering's shopping guide
which based upon the links given there I suspect that Mothering may get a portion of the sale from those links as well.
I prefer either Three Sisters of A Toy Garden, but this last time when I wanted to order something just about everything I wanted from Three Sisters was out of stock. In either case the shipping is fast and I really like the customer service.
ETA: I just saw your other question - if you go to Paper, Scissors, Stone
they list two different kinds - Stockmar and Stone. I've found their site helpful to see what's out there, but have found their prices (especially if you're placing a smallish order) to be a bit more expensive, especially when you add in the shipping.