Not many deals on large, big & tall sleeping bags. Here's one (39x81 inches) that will fit up to 6'4". This has a 50-30'F rating (take that lower temperature with a grain of salt - for survival only, not comfort). Zips together or opens to use as a blanket.
Coleman Oak Point Large Cool-Weather Sleeping Bag [amazon.com], $29.58 @ Amazon, FSSS or free Prime shipping
Lowest price according to camelx3, which says $49.49 is the average price. Costs more at Coleman, Walmart, Kmart, Bass Pro, Home Depot (!), etc.

Also at Target (probably why Amazon lowered its price):
Coleman® Oak Point™ Cool Weather Sleeping Bag [target.com] , $29.99, free shipping

product page at Coleman:
Coleman® Oak Point™ Cool Weather Sleeping Bag, Model No.2000004456 [coleman.com], $59.99

4.5/5 stars in 365 Amazon customer reviews (Oak Point and Dunnock bags lumped together).
Here are the 192 customer reviews filtered for the Oak Point bag only:
Customer Reviews Coleman Oak Point Large Cool-Weather Sleeping Bag [amazon.com]

Note: Amazon lumped the Oak Point Large Cool-Weather Sleeping Bag (4 pounds of insulation, 50-30'F rating) with the Coleman Dunnock Large Cold-Weather Sleeping Bag (5 pounds of insulation, 40-20'F rating) together on the same page, but wrongly use the latter's title for both.