I've been scratching my head regarding why it is so expensive, and whether it would be worthwhile splicing it myself. As you say, there is careful design behind this, starting with a spliced loop that has enough rigidity to stay open. That would be difficult to overcome by home splicing. The pulley is the DMM rig design, which is larger than the regular DMM pulley, and significantly more expensive. It looks like you need the larger pulley, to allow the retrievable ball to get through and then be stopped by the thimble.
The pulley is the smaller size and the yellow (not the RED) retrieval cone slips through nicely. It is not impossible to splice your own with 1 strand rope but they never come out as nice and long lasting as the original item. You can buy just the rope with special eye as a part and then install the pulley and retrieval section as you like, if you wish.
