Welocome richleni!.
If you're ready to buy I'd spend the money on both a CarFax and Autocheck. On the whole I've found CarFax provided a bit more information, however have also seen accidents reported on AutoCheck reports that CarFax hasn't captured.
Personal experience also tells me that both services don't pick up everything. Two years ago both our Avalanche and minivan were pelted in a Texas hail storm that lasted all of 7 minutes. My truck had $3500 in damage, needing a new hood, roof repairs and repaint of those surfaces. The wife's van was worse, $5600 for repairs, painting etc. Neither CarFax or AutoCheck show those repairs on their reports.
In my book, nothing beats an inspection by someone knowledgeable in both body work and mechanicals if you have any doubts.
