Use Google search terms: "solid state tesla coil" AND circuit AND schematic, Turns up 65 hits
There are some mosfet ham radio output stages that use a mosfet driver chip that output 40-50 watts of carrier for an AM transmitter - but simple?
If I wanted a SIMPLE power oscillator in the 100 KHZ range, I'd get a pair of power transistors with a good high frequency response and wind a simple air core center tapped coil and use the more or less ubiquitous push-pull, cross coupled power inverter circuit to drive the tank circuit.
See: He's done just that
If I wanted SIMPLE I'd start with the 1962 "RCA Transistor Manual" for some ideas. They have schematics for a very simple 100 Khz (kilo cycles in those days) ten watt oscillator that uses a single germanium (!) transistor with a 28 volt supply and besides a tuned tank uses only one resistor and one capacitor.
Put a silicon transistor into the circuit and boost the voltage and you have a 50 watt oscillator . . .
They also show a 28 KHZ oscillator for 5 watts.
Again scroll down the page and there's the pretty close to the '62 transistor manual oscillator using one mosfet with an input power of
180 watts.I can scan and post the '62 schematic to alt.binaries.schematics.electronics if you want, but you are just not searching hard enough or effectively enough - the stuff you want is on the web.