
I'm not sure that promoting stand-alone tools purchasable and owned outside of their 'Premiere Subscription' (lease and relinquish) model would work for them. Pre DS 4.23 items will still come up in sales as they are fond of milking legacy items, so if you haven't already done so, put them on your Wishlist, it isn't a guarantee,Wishlist sales are quite good ... sometimes ...
I've not seen many tools on other vendor's site (don't really focus on them), but I suspect* the Tool Devs are kind of hamstrung by the Daz SDK / PA / Dev T&Cs and licenses ...
* I haven't verified that, it is just a cynic's opinion