Huh? Just set your limit to 105 or 200 or 10500. There's no reason to ever use a market order unless there's some other severe limitation on limit orders in a particular implementation.

You can't set your 'limit' to 105, when the current price is 101. That's a market order.

Even if you could, why would you want to buy at 105, when the current price is 101? Just to don't have to pay 0.25 in fees!? That sounds like "The Firm" from John Grisham where rich people would rather pay $2 to lawyers than $1 in taxes.

This is incorrect.

You do not know what the current price will be when you click the submit button. You may enter a limit of 105, and find that when you get around to submitting, the price is suddenly 205 or 1.05. This is why you use a limit order, so that your "market" order doesn't give you a sudden surprise.

On top of that, the current price is only valid for a certain depth. So if the asks are 10x101 and 20x106, I want to set my limit to 105 to make sure I only take that 10x101 order off, and not start chewing through and execute at a much different price than "current". All these orders are changing extremely rapidly for any popular item, so using limits makes sure you get the execution you want.

The limit does not set the price that your order will execute at, but the limit. It'll match at or better than the limit you set. So you never end up paying more than you're OK with, but you prevent getting burned by sudden movements. This is much more important on these cryptocurrency exchanges than traditional stocks.