Steve writes: Can I sell TV scripts like I would a spec movie script? If you send a script for a single episode into a studio would they buy it if it were good enough? And what would the going rate be for such a small piece of writing (relative to Hollywood movies, that is)?
In theory, sure you could. But it pretty much never happens. Writers write spec episodes of TV shows as samples of their writing, in the hopes that they will get staff positions on shows. The idea is that a spec proves you can emulate someone else's style, vision and voice - and thus make a good staff writer. Theoretically, if you wrote a really hilarious episode of something and the showrunner read it and fell in love with it, it could become an episode. But I have never ever heard of that happening to anyone. (A spec pilot is different - plenty of spec pilots are being bought these days...but a pilot is written to be a TV show on the air. A spec episode of an exisiting show is written to be a writing sample.)
You shouldn't ever be sending your spec into a studio. They will send you a mean letter of legalese about how they can't accept it. Sure, studio execs read scripts all the time - but from writers represented by agents or managers. And these reps will decide who to send your scripts to, and for what. They generally will call the execs first to introduce you and pitch you and ask if they can send it.
To answer your question about the money, the WGA minimum payment for writing one episode of a half-hour TV show on a broadcast network is $21,585. The minimum for an hour-long show is $31,748. Cable is a little bit less. It's definitely less than what hot feature specs sell for (sometimes more than a million), but TV writers will also earn weekly payments for being staffed, and will earn more with higher titles, etc. Feature sales often yield more impressive lump sums, but with TV there is a lot of potential to rack up money over time - with staff positions, overall deals, backend, etc.