A limit buy order above the current offer is "marketable" and, for most purposes, is the same as a market order.
I almost never use market orders, preferring limit orders instead in case something unusual happens with the market or the order. I don't expect to get filled at a price better than the offer for a marketable buy order unless routed to the NYSE, in which case I usually will get the next print, assuming there is not a lot of other buying interest.