If you just want a card that can counter split-second spells, an enchantment would probably work better. The idea of a counterspell-land gives me the heebie-jeebies.
Out of Time

Enchantment

, Sacrifice ~this~: Counter target spell. Add

to your mana pool.
I still don't like this, though, because it would be the first targeted mana ability, and that doesn't seem right.
For a land:
Outside of Time
Land

: Add

to your mana pool. All spells and abilities lose split second.