Originally Posted by
sydneyracquelle
Best advice is book a main cabin ticket instead of First. Once it is ticketed you will usually see the price in $ or miles to upgrade to FC. Compare this price vs the actual cost of just buying FC and book the cheaper one. No risk during the first 24 hour risk-free cancellation period.
You can also just click modify flights and just upgrade the ticket to First that way. Did that when I had a seat map buy up at $230 for a JAX-BOS a month-ish ago but the fare difference through modify flights was only $100.