Hey @Gilgamesh - welcome to the community!
I’d agree with @Sjoerdo that site is almost certainly dodgy or a recast merchant. (Whether that bothers you or not it is up to you I guess).
At CDO we don’t officially ever promote knock off Warhammer or particularly discuss it on our open forums. (Not that I think you were doing that btw buddy, you were just enquiring as to the legitimacy of the site.just doing my admin duty by pointing that out.)
I can thoroughly recommend Russian alternative - really great sculpts that fit well alongside LoA. Titan war games have some lovely characters that would also fit. @Baggronor sculpts those bad boys and they are lovely. Linked here. I believe he has a new cannon on the way too. @Admiral ’s Etsy store, admiralty miniatures has some lovely old school big hats but also has a unit of gunners called deathspitters that really fit the LoA aesthetic. Linked here.
Also , I know you ain’t into 3D printing but if you have a mate have that is, Lost kingdom also fit the aesthetic really well. (Our latest podcast discusses these so may be worth a listen) depending on where you are based, there are often CDO guys who are relatively local and happy to help out a friend in need who wants some bits printed.
Glad to have you aboard Gilgamesh and look forward to seeing what you create!!!
PS: Random question. What rules you thinking of using? The legion of azgorh rules are likely to be left to rot now. Does that bother you due to it being a non competitive setting? Some guys do chaos warriors aka slaves to darkness rules and it can fit quite well depending on the style of force you are after.
There is a cool fan made AOS book that may interest you created by @thommyh . If your group are non competitive they may allow it! Linked here