Is It Really Worth Getting Something Graded?

For a single coin its going to cost you a minimum of about 50 with shipping and thats for a modern coin. You can get the average cost down to about 10 dollars a coin with bulk submissions and probably a little lower if your a massive store sending in thousands of coins a year

For cheaper coins it all depends on what you paid for it and what it will be worth as for if its worth it or not. A lot of the really cheap ones are misses though or were the result of bulk submissions

It's nearly impossible to replace a coin in a given slab. What you see along these lines is new slabs with fake coins and labels.

TPG slabbing is useless for coins whose value is under, say, $150 unless they're a popular variety with great liquidity, and authentication is important. That's the mistake most people make - thinking about slabbing in terms of cheap coins. Of course that's not a viable option.

IMO there are three reasons to get a coin slabbed.
In order of importance (high to low) they are:

1. Authentication - is it really what it appears to be.

2. Alteration - has the coin been "adjusted" in some way; cleaning is the main culprit.

3. Grading - notice I rank this as the LEAST important function of slabbing.