When considering a used bike I have a few questions I'm hoping someone can provide direction with. Looking for a road bike for fast paced distance riding both on roads & paved trails. My price range is about 300-800 depending on the bike obviously. I understand all these questions depend on many factors but just general information and guesstimates will help a lot, please.

1.) How old should I get and where should I draw the limit in terms of age. I've been told new Sora/Tiagra parts aren't the best but I can't imagine a 6 year old Ultegra would be better than a new Sora.

2.) While prices vary based on a lot of factors can someone please give me general costs of things to look for on used bikes, otherwise I don't have much of a choice of either just paying whatever or posting here and asking for more help every time I see one that might fit. Maybe find the MSRP on bikepedia and pay a % of that as a rule based on the year. Any way of determining a good price will help.

If you could give me examples of bikes with prices so I could compare them to what I find that would also help a lot.

Thank you in advance with more thank you's to come based on usefulness of information and help provided.