I'd recommedn you hang on to the PCM now that you are into flashing your own. Always make sure the battery is fully charged, I also always pull out the fan fuses just for extra precaution since the fans kick on during the flashing..if the battery drops belows a certain voltage during the flash process it will loose communication and the PCM will no longer work...thats where the extra PCM on hand becomes handy.
You can send the bad PCM off to akm cables or Ion to get socketed and reflashed with a n initial flash so that you can use it again...or buy a Pocket Programmer and a convertor socket and do it yourself once the PCM flash chips have been socketed.

As far as extra PCMs, if your not in a hurry, watch ebay, you get find them on their for about $50-$60 alot of times, I have 4 spares from there since I have 2 LTx motors and do alot of flashing for people.