If your MEA is going to be 9,000 - 10,000 an F will be fine. If it is going to be higher than that, then a turbo might be needed, especially if you have to fight headwinds over the granite clouds below you.
Which takes us back to your question - how much to spend? You will eventually find that you can find a decent F for anywhere from 45,000 to 60,000. Below that, things will be missing which may give you pause (no IFR GPS, engine well beyond midlife, tanks that leak, corrosion, etc). Above that, you will find F models fully kitted out with things that are shiny and kewl, but not really needed for an F to fly from Boston to LA.
As well, it is likely that aircraft in that range will be well looked-after and they will show it. Paint and interior are nice, but engine and airframe are what really count. SB 208 for rust on the steel frame. No corrosion on the spar and a stiffener already installed on the stub spar. Tanks that do not leak. An alternator instead of a generator. A skytec starter. An engine monitor.