SnapNames or NameWinner
 

Should I be woo'd by the higher price tag on snapnames or should namewinner do the trick?

Or should I just abandon both and write my own script?

Depends on what your individual domain acquisition strategy is.

Well basically I'm building massive lists of domains from dmoz/google/dictionaries/3letter generators/etc and sorting them into databases by source, expiration date, PR, Alexa ranking and other stuff. I'm hoping to filter out a few gems from there :glugglug

Well the domain game is complex. It seems everyone has their own angle on the best way to go. Its very difficult to acquire an expired "Gem" though without paying a significant premium using the qualifying factors you indicated. You'll have competition everytime.

snapnames is the best in the market at the moment but namewinner is good for not so "Gem" domain names because it could be cheaper.