Do you already have guinea pigs or are you thinking about getting some?
If you already have them, are you considering putting them outside because of the smell? If so, then might I suggest that you instead alter your cage set-up so that it is easier to clean and easier to keep smell-free.
Go to guineapigcages.com and take a look through their photo gallery. There you will see the many ways that people keep their piggies.
For an example, my cage pictured here cost about $45 to make/put together. I also bought fleece on sale for the lining and fleece "potty pads." I change out the potty pads every couple days and then wash the pads and the liner once per week. Other than that, it's just a matter of sweeping of the poos each day.
The cage is about 30" x 60" (2x4 grids).