You'll need an 8 input audio interface. The MOTU Ultralite mk 3 is a nice cheap and cheerful interface that should give you what you need. Of course it's not the only one around though, there are others to choose from as well.
If you want to buy used gear, you can probably pick up an older MOTU 828 mk ll on line for a bit less than the cost of the Ultralite. They're not difficult to find for sale used.