The iPad has either a 16, 32 or 64 GB flash drive but we don't know how much RAM it has. It wouldn't need a lot more than 1GB RAM because it isn't a big OS, the iPhone has 256MB RAM and it gets along fine.
You can get up to 16GB in most stores. There are 32, 64 and 128GB memory cards, but they are very expensive or not in mass production yet. The 32 GB cards are now more available and it is lowering...