I recently purchased a cheap ($50) optispark online. The quality appeared OK upon inspection. I took it apart and inspected it.

I was wrong.

When I tried to start the engine it cranked VERY hard. The starter was labored and the battery did not last long. If I held the throttle to the floor it cranked normally. (because without fuel present in flood-clear mode the preignition wasn't fighting the starter)
I was eventually able to get it to start, but it would die if the RPMs fell below 1200 and there was a ton of preignition below 1700 rpms. It seemed to be fine above 2500 RPMs.

So what was the issue?
The opti was assembled wrong by the manufacturer, with the rotor flange pressed on in the incorrect position resulting in a ridiculous amount of timing advance.

Here is a photo - the bad opti on the left and a good one on the right. Both are in the exact same position when looking at the other(drive) side. Avoid these pieces of junk! Although - the cap and rotor aren't a bad deal for $50, and they look to be decent with brass terminals.
I ended up buying a new unit from Petris Enterprises, very pleased with it so far!

 

Money talks.

 

Absolutely you get what you pay for! And an Opti is one place you def do not ever chince...