it can only go down if there's regulation. or valve fucking up an update like did making gloves and knives more accessible but i don't remember exactly why if it was the contracts that made them 100% craftable or the case x-ray scanner. I didn't follow since gloves and knifes were the price of a gaming PC. my skins are $200 max no more than that each.
If you ever plan on buying skins i suggest you buy off steam market since you will only be able to sell it off for money out of the official market. Otherwise, you are setting yourself up for failure; off official market the skins are a bit cheaper if you buy them on the official market they are expensive. There's like 10-33% difference.