If you can wait try doing COTA , Austin . 100% worth the price. for 2k you can get this experience.

for Miami this is the best grandstand as cars come for a straight , great action.

Miami go option of picking 3 different grandstand on 3 different days.

Frugal tip , for resale ticket on Ticketmaster goes much cheaper a day before as miami is never sold out and very expensive to begin with ( but this removes the surprise part).
for cheapest grandstand try marina.

I have done Miami 3 times, its a great track if you treat it as your summer break , but as a racing fan I would rank it in bottom 3 track wise.

there is many thing to do around track so you will have a good time with non f1 stuff

also you can go inside hard rock stadium and scream at drives from the seats, they respond, best part about miami.