You pay more because they're highly detailed and come with a fair amount of customization. Depending on the kit, they come with multiple heads, weapons, and even some accessories.
At $50, that's only $7.15 a unit which is fairly decent for a well made miniature. With miniatures in RPGs, I find it's generally easier to stick to purchasing and painting models for PCs and special monsters/NPCs such as beholders, orc bosses, dragons, etc., etc. but it does become cost prohibitive for many people when you start purchasing minis for rank & file enemies like orcs, kobolds, goblins, etc., etc. Honestly, at $50 for seven miniatures, I'd rather go to Games Workshop and purchase a $42 box of 20 grots (goblins) which comes out to $2.10 each. I could get 20 savage orruks (orks) for $60 which is only $3 each.
I really like the WizKids monsters they produce. This is a very large Magic the Gathering Wolf they make and it's a good value at $16.00. I have not been a big fan of the humans, dwarves, elves, or other PC type miniatures they make. The sculpts are okay, I guess, but I don't find them aesthetically pleasing. I think WizKids is trying to directly compete with the likes of Games Workshop with their sprue miniatures. A significant percentage of gamers will continue to purchase the cheaper non-customizable miniatures that are currently being sold. (And are a good value in my estimation.)
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