I just found this and it looks interesting. I haven't tried to build any of my own circuits but this would be a great tool for creating schematics and trying different values.
I looks like the free version is a limited trial and then there are three levels of membership at $40, $65, or $200 per year depending on the features you want.
Schematic editor and circuit simulator.
Build and test circuits right in your browser!
* Design with our easy-to-use schematic editor.
* Accurate analysis (DC, AC & more) in seconds.
* Beautiful schematic printouts (PDF) and images (PNG).
* Share a live circuit URL so others can simulate and edit your circuit.
https://www.circuitlab.com/ (https://www.circuitlab.com/)