As far as I know, there are no free on line price guides for the vast majority of stuff that gets traded here.
There is SMR (for graded cards).
Beckett is a subscription servce. I avoided it for years, preferring to buy an ocassional paper Beckett and use that. Then Beckett split their listings and put vintage (pre-1980) in a separate magazine, so I'd have to spend $10-15. In addition, the print in Beckett got so small I could hardly read it. I finally gave in and signed up for it and am glad I did. The amount of time I have saved using it the past month or so has more than paid for the subscription.
Boots