Sidacs can be found reasonably online. Test the resistor (of the dead ignitor) first! Any good multimeter should have a few ohms settings.

I bought a lot of twenty of those wafer open GE ignitors on ebay nearly 10 years ago. I must've payed about $35-40 USD shipped, so each ends up at about $1.75-2.00. I've seen a few (not many) such ignitors on ebay since, but now the exchange rate and the Global Ship program most US seller are dealing with is a killer for us Cunucks. My offer for 2 of these wafers still stands. Mailing that sidac is one stamp to Canada.

I don't really want to order it.

I think there is not much other possibilities left than really ordering it from some electronic part distributor (Newark, RS,...)...
Most of them carry even the required inductors...

By the way what is that wrong with these? I may understand the postage for a few cent component is relatively high, but on the other hand we are talking about the key component in the ignitor...

I just don't want to wait a week or 2 for them to arrive lol, I have no problem ordering, just shipping tends to be slow internationally and I'm the type of person that wants to get on with things that I really want to do lol.

I replaced the caps, that did nothing, and the resistors are fine. I tested them on the meter and it said what it should say. The inductor looks a bit cracked so it's probably that? If not are SIDACs known for failing often?

George, what site do you order the SIDACs from and how much is shipping usually?

The inductor is quite easy to check for the most common open circuit fault - by the ohm-meter. You should see something between some 10 to 100's Ohm.

The 100V SIDAC (for the series reactor ballasts for the 55V HPS lamps) you may quite easily check as well:
1) An Ohm-meter should read an open circuit
2) Connect a regular incandescent bulb (20..40W) in series with the SIDAC to the mains, the lamp should light at a reduced brightness, but without any 60Hz flicker. If you own a variac, you may try to connect the lamp to the output and observe the response. The lamp should remain completely OFF from zero till about 70..80V, then should rather abruptly light up to reduced brightness. A small region (5..10V) where the lamp is flickering at 60Hz (only one polarity conducting) is OK.

The 200V SIDAC's (for the lamps with arc voltage of 70V and above, so S56 and higher wattages) could be tested principally the same way, you only need all voltages double. A 120/240V tapped ballast primary used as a step up transformer and either 240V or two 120V bulbs in series would do the job rather safely (for a lab test purpose).

Except for ebay I haven't bought these parts online. Medved's suggestion for ordering from newark.com is ok but you need to order a quantity!

The sidac from other ignitor: http://www.newark.com/littelfuse/k1200e70/sidac-1a-to-92/dp/60K6148
Same item on ebay http://www.ebay.ca/itm/151909179750 & for 10 http://www.ebay.ca/itm//151909179662

I also could not find even online 16mh inductors. There is every number but 16mh which is weird. I went to my local parts shop and got some 10mh inductors. Would those work?

I also can't find 16mH online or on ebay. Then what you need to do is work with what's available. Add the inductor values for series, like 10+6 mH.

http://www.electronics-tutorials.ws/inductor/series-inductors.html
http://www.electronics-tutorials.ws/inductor/parallel-inductors.html

P.S. The inductors need to be "high power" & the resistors have to be rated for 5Watts or more.

For this purpose the 10mH will be OK as well.
There is even not needed anz high power rating for the inductor, 10..15mA current rating is perfectly OK...
The coil has nothing common with the arc current, it is there to just increase the impedance (for the fast ignition pulse) of the capacitor charging branch. The inductance is not that much critical, anything above 10mH works well...