Typically if you rollover an IRA or Roth, unless the place your are rolling into has access to the same mutual funds, you won’t be able just to transfer the funds over. Usually when to do a rollover, you would initiate a rollover request from the old place, and that would cause your funds to be sold. You would either get a check in the mail or you could do it electronically. You then have a short period of time to deposit it into your new account as a rollover. You get a tax form that shows the amount you rolled over, so you won’t be subject to taxes. And that’s it.

There certain cases when shares can just be moved over. It is unlikely if you move into vanguard, that will be the case for you though. However, call vanguard to double check.

Depending on how much you are rolling over and what funds you select, you may be qualified to buy their admiral shares which are lower cost than the non-admiral share equivalent.

I would also compare the performance of your old fund versus the new funds you are planning to roll into.

If you are just sticking with index funds, then that probably doesn’t matter as much. But if you are moving between managed funds, I wouldn’t just be considering cost.