Could you estimate the cost of travelling to Panama City, Panama from Nogales, Mexoco by bus?

The Mexico prices the other guy cites sound higher than I remember, but prices probably have gone up. Try ticketbus.com.mx

In Central America, it would be significantly cheaper, but also a lot less convenient and slower, to take the local buses rather than the Tica. On the other hand, why take the bus at all if you're just passing through, rather than fly? The second class buses, which are like school buses, are rock bottom cheap, like $0.50-1 per hour of travel or so. I recall going the length of Nicaragua for something trivial, like $6 or something. The pullman or express buses aren't much costlier, although they're funkier than Mexican 1st class. If you're lucky, you'll get a 40-year old ex-Trailways bus with gringo leg room.

Ejecutivo Class/One Way/One Person

Three legs/Three buses $300.00+/-

Nogales-Mexico City $120US

Mexico City (Oriente)-Tapachula $75US

Tapachula-Panama City via TicaBus $105US