After seeing someone on here camping and travelling on their bicycle, I have decided I would like to give it a go.

are there any recommendations as to bikes which would fare well in any climate, uphill, downhill and whatnot? also any aftermarket seats .
I would spend up to around $400, could push it a bit for the right bike, if there are any bikes that can be bought relatively cheaply on the second hand market that would be cool too!

thanks