Part 103 planes have had a hard hit since 2005. There is plenty of what went wrong stories and I am sure moderator Tim B can easily do that.
So let's look at what was part 103 and where they might be right now -
Part 103 had reached a base of aircraft by 2000. Many had come and gone by then.
Survivors - TEAM with the Ison designed aircraft - now in limbo between owners. - wood
Fisher Flying Products - now out of Canada has the FP-series - also wood.
Quad City Challenger I - careful weight control + engine selection
sorry I missed others...
All of these require great diligence to make weight - using the lightest paint (acrylic), no build it better diversions from the plans, light wheels and tires, minimal panel and creature comforts - engines: singles and only the lightest twins will work.
"New" players include Belite and Valley Engineering

Challenges - Rotax looking at the market is now discontinuing the 503 engine as well as all smaller ones. No worries there are plenty of inventory and spares to go around for a long time.

Smaller engines needed for weight making are not as exciting a ride at 500 fpm.