How do I create a classified ads with different platform?

Hi!

i am planning to create a classified ad for personal experience using EE.

There would be 3 different platforms Buy/Sell/Swap for: Audio Apps and Plugins Studio Hardware Gears Music Production Packs

I am stuck at creating channels because each platform will have different fields

also if there will be users who want to post, what do they see on the new entry? is it the channel name? if it is, should I name the platforms as:

Post Audio Apps and Plugins Post Studio Hardware Gears Post Music Production Packs ???