The idea that the solder WMS used is gone like the dodo bird is internet lore that is not 100% true. A call to Kester will confirm that the part number just changed.
Personally, I prefer 63/37 solder. Melts at a slightly lower temperature, which is a *good* thing, which allows you to get better results with less heat.
Considering all that, what PBL charges for a roll of this mystical solder ($100 last time I checked), and the fact that it should still be fine, $30 doesn't seem to be out of line at all.
Why you want *good* solder, and not just whatever is cheap - the good stuff flows well, and cleans up easily after rework. Cleaning flux is one of the biggest pains in the a** of working on boards.