I'm not clear from your post as to what you're wanting to do.  Are you wanting to program a show (1, 2 or 3 hrs) or program an entire radio station?

It is much, MUCH cheaper to own an internet station than it is an FM station.

There's also no reason you couldn't do both.  If you have station willing to put you on, there's no reason you couldn't record your shows & put them online.

OTOH, if you were thinking of repeating an FM station's signal or another online station...  well, if the FM doesn't have a stream they may be pleased but you'd still need permission.  The internet station might or might not be pleased, depending on whether or not you were trying to label it as your own and steal eyeballs from their website.

If you were planning to repeat a local FM on FM...  it's done, but unless the signal is weak in your area I don't really see the point.

Can you clarify?  Perhaps then I can help you more.

Um...  at the risk of the meds I'm taking for my head cold doing the talking...  you can go WAY low power on both AM & FM and not be licensed...  but the power requirements / antenna requirements are both so restrictive that you're lucky with FM to get across the house, much less across the street or down the block...  right?

AM can give you, what, a 1/4 mile if done properly?  Still not much.

If that's what he's asking about, here's the questions to ask:

#1 - How close is your audience?

If you're in an apartment complex & your station targets the tenants, you may have something.

If you have to walk off your property to get to your next listener, you'll do better with AM or internet.

#2 - How tech-savy is your audience?

If you're targeting 12 - 17 yr olds with underground dance music, they'll listen to 100 internet stations before they'll switch on an AM radio.  (And they'll likely do it on their iPhones, adding insult to injury to us "old-timers" who always listened from a desktop.)

On the other hand, if you're doing oldies or standards or old time radio, your target may do better flipping on the radio instead of trying to figure out how to get to your site, get their speakers on, what link to click, what player to use, etc.

Tell us what direction you're wanting to go, & we can help guide your purchases.

RRRRRRRRRRRRRRRR Ya B a Pirate matee. ya best be careful of the FCC.

Part 15; EXACTLY, Richard...  that's what I was doing such a lousy job of trying to explain. 

I mentioned using FM for an apartment building; an even better option there would be carrier current.  As long as somebody's close to the walls, they can hear you...  and I'm 99% sure that would fall under part 15 rules as well.  (Double-check me, though.)

...Where'd Beat104 go, anyway?