User Review: Kelty Men's Mistral 20
Price Paid: $40 at sunnysports.com
Bought the LARGE size for sleeping in my toy box with the furnace set to 55 to conserve gas and battery or in the back of the pickup when I'm car camping in the desert and it isn't going to get much below 40.
Using my rule of thumb for cheap bags that you add 20 degrees to the specified temp rating to get the "you won't be shivering" rating, it works as expected. Has plenty of room, cost $40 and hasn't lost too much loft in the 20 to 30 nights I have slept in it.
If you really have to sleep in sub-zero temps buy an EN rated bag and only add 10 degrees to the specified temp rating. Generally, Kelty makes decent stuff for the dollars and this is no exception.