Have a look through this thread here - there are as many options and solutions as there are spaces!
http://www.theguineapigforum.co.uk/showthread.php?t=53210
Many of us indoors people favour C&C grids cages with a correx/coroplast tray and fleece bedding, because they are comparatively cheap and allow flexible set ups that make the best use of any available space.
However, if you also have other bigger pets, a traditional cage may be of more use to you. If you are in Britain, members can provide you with links on where to get the current best offers in our housing section. But I have also seen setups that have been cleverly integrated into bookcases on the continent where space in flats was an issue and people wanted best access and visibility!
A cage for two guinea pigs should be a minimum of 2x4 ft (60x120cm) as per RSPCA recommendation. Especially if you are going for two boars, more space would be of advantage, (2x5 ft or 60x150cm). Please note that unlike with rabbits, neutering boars only removes their ability to make babies, but it does NOT change their behaviour!
If you would consider rehoming from a reputable rescue, you will get properly bonded, sexed, not pregnant and guaranteed healthy piggies as well as support during the settling in period; something that sadly pet shops and many breeders have not the time and experience for.
Great that you are doing your research beforehand!
