You should just book your reservation now for fox. In the mean time you can keep looking at the various web sites (kayak, carrentals.com, etc.) to see if the other companies lower their rates. Because you are looking at November the prices might be high right now. As it gets closer to November the prices will fluctuate. It will all depend on customers renting at the time, the car rental agencies probably have a program or something, if they notice that reservations for that period are down they will lower their rates until they get more reservations and raise them if they get an influx of reservations.
What I do is to make a reservation now so you have a base reservation with a set rate, then as I find lower prices I would book those and cancel the higher reservation. I would check November rates maybe every week or so twice a week right now but as it gets closer I would check more often, sometimes every day. I find that a month or two before your visit the rates might change daily. Locking in now guarantees you the $90 rate and you can work your way down from there. During busy times like conventions, new years, etc. the rates might go up as it gets closer so it's best to at least have a reservation and set rate now.
The great part of car reservations is that you don't have to pay anything and can reserve and cancel at any time without penalty up to the time of your visit.
You should do a search on this site and other sites for fox rental reviews. Many say that they won't ever use them again (bad experiences). Fox always seems to have the lowest prices but many people complain about the lack of service, slow service at the counter, long lines at the counter, availability (or unavailability) of cars and overall bad experiences with them.
as jm mentioned, you will have to take the airport shuttle to the car rental facility and then pick up the fox rental shuttle to get you there.
As I mentioned, IMHO you should just make a reservation now and check the rental sites and book and cancel if you find lower rates. I think you will probably find something lower with the national chains as it gets closer to your trip, maybe even getting a larger car for those rates.
good luck!