The cheapest way to buy into Surface will be the $499 base model. This will give you 32GB of storage, but won't come with a Touch Cover membrane keyboard-cum-cover. $599 will get you a 32GB model with a black Touch Cover, and $699 a 64GB unit, also with a black Touch Cover.
Standalone Touch Covers in black, white, magenta, cyan, and red will retail for $119.99. Type Covers—a clicky keyboard with actual key switches—will come in black only, and cost $129.99.