In my last post I talked about affordable choices. When you learn what suits you, you might decide to try something from the luxury end of the spectrum. What should you expect for $100 or more?
Shootability - pick a style that suits your shooting style and has a good reputation as an accurate slingshot.
Durability - if you are going to spend heavily on a slingshot, you'd want it to last. Some materials are harder to work, cost more in labour, tooling and consumables but can last a long time. Strong metals like aluminium, brass, stainless steel are durable and more likely to survive a fork hit, but may sustain cosmetic damage, espcially if they are combined with exposed wood. Micarta and especially G10 may survive a fork hit undammaged (but for safety's sake always check).
Style - it's got to look kick-arse awesome and really stir people's desire. The design should be unique and the finish flawless.
Collectability - a big name maker, or shooter's endorsement, limited editions, good exposure, exotic materials all contribute to collectability.
In the knife world, there are plenty of knives that command prices in the hundreds, thousands and even tens of thousands of dollars. There is no reason why a slingshot should not have the same value if there are collectors and worthy product.
For the time being though, stick to what you can afford.