Those who own Avalon equipment or have looked into it will know that it can be pretty pricey. I have the Avalon M-Uno mount, which is fantastic in its own right, but accessories for it can cost an arm and a leg. The mount in itself is designed in a way that it mostly does not need counterweights to balance the entire optical train in Right Ascension. Indeed this is one of the selling points. The unique design of the fork arm allows the user to place the form ark in one of six different positions, which causes the moment created by the optical train to be balanced purely through the fork arm. Of course, minor adjustments may be necessary and this is where the caveat comes in - a small counterweight bar and a tiny 0.55 kg counterweight are included in the package. At the very least, you have to carry much less weight with you to set it up. However, sometimes your chosen optical train will just not balance. My Altair Astro 8" RC telescope with all the bits attached to it simply would not balance even on the heaviest form ark position.
When I bought my Avalon M-Uno, I bought it with an extra 1.372 kg counterweight, which is Avalon's heaviest for the M-Uno. Using both was just not enough. I decided to purchase a larger counterweight and found that Avalon do not make any. Fortunately, Ian King from Ian King Imaging came to the rescue! He knew a company near him that would be able to manufacture these to specification and is stocking 2 kg counterweights for the Avalon M-Uno. You may need to e-mail him for them though as his website does not appear to list them. This is the 2 kg one I ordered, which cost me about £68 without UK VAT (about £82 with UK VAT):
What is nice about these custom-made counterweights is that they are very much like the original Avalon in design, so they suit the mount perfectly. In addition to heavier counterweights, one can get an extended counterweight bar for the mount, which is by Avalon, at an unfortunately high price tag of around £165 including UK VAT. This is the extended counterweight bar with the above 2 kg counterweight attached:
Together, these produce a fairly large moment on the Right Ascension axis, which allows balancing heavier optical trains than the mount originally allows balancing (while not getting anywhere near the mount's maximum rated payload capacity).