@Your_Fan To the best of my knowledge R* and its parent company don't own or operate this site. Other than drm take downs, they don't have any involvement, and if they read the forum posts here about the grief caused by each update they certainly don't show any empathy.
I've never seen the site sell anything here, like Amazon or ebay, so certainly isn't common and possibly a violation of the TOS. An admin can provide a proper answer.
If you have extra money you'll easily find thousands of GTA5 patreon sites selling conversions of video game assets and even some made from scratch.
On some 3D modelling sites, a professional character can cost you $600 U.S.
Find someone to convert it and you'll have an incredible and exclusive ped model for under $1,000 U.S.
Oh BTW, don't equate price with premium quality. Even the preset modders, which means a Menyoo xml file, have patreon sites to sell their work.
There are also skilled modders who will give this community their crumbs, expect praise for their contributions, and make you pay for their real mods.
And of course there are amazing mod creators who are strictly community minded and don't beg for financial support.