Send her the Starter kit (if she can't find it) It's like $13 with S&H, so I think you can afford it. After that, send her a box of extra cards. It doesn't have to be big, and it should cost around $4 for the small card box and the shipping. Send a step by step guide like this to her:
Untap phase
Untap
Draw phase
Upkeep
Draw
-you can play instants and activate abilities of cards in play at this point
Main Phase
-You can play sorceries, instants, summons, enchantments, artifacts and activate abilities abilities both before and after you attack. You may also lay one land before or after you attack.
Attack Phase
Declare attackers
Declare blockers
Put combat damage on the stack
Apply combat damage
Bury any dead creatures
End combat phase
-you may pay instants and activate abilites at any time
Main Phase (again)
Clean Up Phase
Discard down to 7 cards in hand
-you may play instants and activate abilities
End Turn
All the little rules loopholes and strategy of decktypes can be saved for later. If you include a couple of premade decks, type up a sheet of basic information for her to read, like the ones that come with the preconstructed decks. Here are a couple of cheap decks to build to send her
4 Goblin Patrol
4 Kris Mage
4 Mogg Toadies
4 Goblin Raider
2 Goblin War Buggy
4 Wild Colos
4 Hulking Ogre
4 Seal of Fire
4 Shock
2 Parch
4 Arc Lightning
20 Mountian
4 Seal of Removal
4 Wall of Glare
4 Miscalculation
4 Counterspell
4 Snap
2 Cho-Manno's Blessing
4 Accumulated Knowledge
4 Horned Turtle
4 Task Force
3 Stinging Barrier
2 Vigilant Drake
8 Plains
13 Islands
4 Wild Dogs
4 Llanowar Elves
4 Pouncing Jaguar
4 Acridian
4 Spinless Thug
3 Undertaker
2 Blanchwood Treefolk
4 Vendetta
2 Snuff Out
2 Pestilence
2 Symbiosis
2 Spidersilk Armor
11 Forest
12 Swamp
Just for a start. These decks should easily cost less than $5 each, even if you don't have any of the cards.
Good luck,
Erik
