So you can buy 500,000 Gold legally in the game in the Optional Item Store

[Risvertasashi]

IF you want to talk about real P2W, the closest you'll get from that store is the Cloud Bike.

But even that isn't going to have much of an impact anywhere except maybe Bozja for new players.

New expansions too. Get that speed boost in the new zones without having finished MSQ nor with any need of riding maps.

But to answer the OP's question - yes, you can buy multiple boosts, but gil is so devalued that as others have said, it's basically nothing. It's a bit of pocket change SE gives to partially make up for not making money as you level.