Please learn as much as you can before buying a guinea pig
Top tips for happy piggies!
*Guinea pigs are social and do not do well alone. They will be chattier, more active, healthier, more outgoing and generally happier with a friend of the same species. Please do not house your guinea pig alone, this is actually a law in some parts of the world.
*Space! Don't buy a tiny petstore cage, do some research and buy a cage that is 30 x 36 or larger. With more space, your cage will stay cleaner longer, you can add more fun things for your piggies to play/hide in and have more enjoyment watching them. And of course their exercise ability and quality of life will be better.
*Do your research on bedding options. Guinea pigs are messy and will need their cages cleaned every 5-7 days in general, depending on your cage and how many piggies. Wood probably has the best absorption and is the least expensive: pelletized horse bedding, pine or aspen shavings. Carefresh/yesterday's news or other recycled paper bedding is an option, or even fleece (if you're OK with doing some laundry). Lots of info online, check out the pros and cons of each.
Below are some links that may be helpful:
Can my guinea pig live alone?