make sure you have it gapped right too. when i did mine, the first time it was too far out. ended up using a piece of paper as a shim, first time was a business card. i think its .0125 or something tiny.
just so you know, the mower i did this to-- the guy said it would not start, and had no spark. he played with it for a while, got mad and bought a new mower. i gave him 50 bucks for his old one......
he had lost the spark plug, a few bolts but the thing even had aired up tires and sharp blades on it. it was FUN mowing the yard on my new mower-- even had a half tank o'gas.
you have it apart, tomorrow try it again!! all the hard work is in, now its what 2 bolts and a plug removal?
also, see if you can borrow a coil before you buy one. might be tough (depends on the neighborhood-- i have a few neighbors with parts mowers) but money saved is money earned.
i have good luck with putting part numbers in google and comparing prices that way. currently looking at a filter for the above mower, and have at least one option cheaper than the best price i found on ebay-- shipping included.