I honestly believe once you find a bargain you should just take hold of it as soon as possible.
Prices tend to buildup the closer you get to the date of booking influenced by their availability.
It is worth looking at some other sites to compare prices.
If you can't find lower than $136 I would recommend to book that one.
what I would not recommend is going without booking a place to stay first, It is pointless wasting the first day frantically looking for a place to stay, and usually spending extra money to find a place on the day as you are left with less selection because time is running out.
Try using the "build your trip" flight comparsion tool here:
Las Vegas Flight it will search multiple websites and get you the best price.
Have a fabulous time in Brasil!
I hope my reply helps.
Links of interest:
Las Vegas Hotels Cheap Las Vegas Hotels Las Vegas Strip Hotel