RWM is also still pretty cheap. 25USD for 8 models and their tray/cards? 40k will only give you 1 model at that price. All the unit packs are around 50USD or higher for anywhere between 4-10 models depending on their size or "elite" status (some things are stupid expensive simply because the units rules are "better" than others)
The cartoony nature lets them produce cheaper models because cartoon design by default masks a lot of the realistic issues painting, drawing, or modeling comes across. I prefer a neat artstyle rather than super duper realistic features, it makes it feel more unique. Theres a reason i dont like most "realistic" video games, they all look the same to me. My room mate was playing a LOTR game (shadows over mordor?) and until he said something i thought it was some vague Assassin's Creed game for awhile.
You will probably spend easily 1/4th if not less on RWM than you do 40k. I have Orks and Tau for 40k, and BOTH armies are around 3000USD worth of stuff...and i know many many people that dwarf my collection.