There was a Barnett limb on ebay for 99 dollars, which while a whole lot more expensive than 12, short of carbon fiber limbs for match bows, is pretty much the top of the line.
Of course, I am assuming we are not talking compound X-bows. They operate against much higher pre-loads, and use the pulley system to achieve much higher string speed. I wouldn't try fixing one of those.
One issue with X-bows is that they are typically left strung, which is also how I leave my stick bows, when I am using them. But X-bows may be strung factory to grave. This means that they are under a significant risk of creep failure if there is anything wrong with the repair.
I have a pal who is an excellent archer, at one time he won top honors in Ontario 3D. He has always shot really heavy bows. 100 pound compounds, and 80 pound recurves, until a few years back. He has been in the archery business his whole life, so he know what the deal it with care and use of bows. The interesting thing being that he has had a series of the best bows made suffer riser failure. The first bow this ever happened to was an early Black Widow, back when they made them with the blond riser. This is significant, because BW was the first company I ever heard about that not only said you could leave their bows strung, but you should. They figured the risk of damage in leaving them strung paled, in comparison to the risk of hurting the bow in stringing it. BW bows were not the only ones to fail he also broke some Checkmates, and a Martin Super Diablo. And when I say broke, they failed in normal use.
He tends to put it down to a run of bad luck, but I put it down to the fact he has a draw weight of 80# + and the bows, while sold in those weights are not failsafe at those weights. I believe that generally a bow like an ASL would not fail in the same situation because it has continuity of backing fiber, though so too does the Super Diablo.