When trading there's always risk involved from both parties.
To help prevent risk there's usually two options people choose:
1. Buyer pays in increments for what they're buying
2. A middleman is used as a trading mediator
I would recommend the second option. You can find a list of available middlemen here: https://osbot.org/forum/forum/122-middlemen/
Just post on threads that you take interest in, engage with the community whilst doing so. It'll take a bit of time but that's why the rule was implemented in the first place
Also don't post on older threads as it counts as a forum offense known as gravedigging
Specific prices are very hit or miss with 99 stat accounts. Cooking, Fletching and Crafting are the more low end accounts at around 20-30m at this stage, whereas others 50m+ dependent on the buyer