telenick spouts good advice...

Don't expect a full fit upfront for nothing. Most bike shops I've had experience with will give you a basic fit for free when you buy a bike. They'll put the bike on a trainer and help make sure it's the right size (fit type one as telenick describes). They might not (and probably won't) do this when you first come in test riding bikes; they'll wait until they're reasonably confident that you're going to buy a bike from them.

If you go in at a quiet time (weekday mornings can be good) they may have more time to spare and might be willing to spend more time with you for free (e.g. adjusting saddle height/position, stem length on multiple bikes).

Some shops will credit you the money you spend on a full bike fit with them if you go ahead and purchase a new bike from them (fit type three, which is usually $120-150, takes about 2 hours).