Before spending $155 on an extended warranty service plan (which almost always are a waste of money) make sure it's worth it over what the standard (two year?) warranty will already cover.

Secondly, you said you're a tinkerer so why not learn how to fix the stuff yourself? Most things are very easy to do with a few basic tools.

I'd buy the new bike and over time amass some upgrade parts for the old bike on craigslist.