Tesla coil power supply?

My Tesla coil is 3 inches wide, 14 inches tall and it has 900 turns of 28 AWG wire. I need to know what kind of power supply will be necessary to power it, car ignition coils only give me 3 inch sparks to a ground.

The most common method of driving the primary on Tesla coils your size is a neon sign transformer. (Sometimes reffered to as an NST among coil builders).

Thats what I use on my coil. I found mine on ebay, and had to spend about $50 for it at the time. Look for one with a higher voltage output, like 9kV or greater.
How many watts should I drive it with?
The NST you want will be powered from 120VAC (assuming you are in North America). The design of NSTs is such that their output is current limited. So, even when the output is short circuited (which is what happens when it drives a spark gap on a Tesla coil) the current on the secondary of the NST is limited to a certain maximum value of about 30mA to 60mA. As a result, the power output is also limited. A typical value would be 300 to 600 watts. The max output current and transformer wattage should be listed on the name plate of the transformer.

It is common to drive the 120V input of the NST with a variac ( a transformer with a varible output voltage) to limit the output voltage of the NST. If you drive it with a variac set to less than full output, the transformer will deliver less than its rated power.
I might be using a modified microwave transformer witch can output up to 2000 watts. But what I need to know is how much will this coil require?