Hello from Melbourne, Australia.. Can I assume the Napa you refer to is in Ca, USA ?
your saying you would like to get to retro computers of the period 70's to 80's but none around you.
So my comments and question in the hope they help you are.
1. Are you looking to only get into the retro for the software side of the that period machine or are you interested or willing to fiddle & work on the hardware side ?
2. can you give a brief indication of your electronics skill level ? Can you use a multimeter, can you solder ? and read circuit diagrams
3. what is your budget ?
4. there are such things as single board computers (SBC) from the period your interested in. These come up from time to time and if unboxed can be low cost is $10 to $120 and cheap $15 to $30 to ship around USA or for that matter the world. If they as most had, a serial port for connection to a terminal, then you an connect them to a modern pc with a serial port and use a Terminal program to explore the retro single board computer board. Ok you would likely need to add a power supply to this SBC, but most electronics outlets or like would have a supply to suit.
So here are a few pics of different single board computers for you to better understand this side of early computing.
1. Vintage Southern Cross Single board Z80 Computer Kit V1.21 sC1 currently on ebay out of the UK for US$129.
2. Intel SDK-86 8086 Logic Trainer Single-Board Computer System
3. a book on subject of interfacing SBC for us$20
http://www.ebay.com/itm/INTERFACING...710802?hash=item2114318692:g:prMAAOSwARZXn6SV
4 KIM-1 Single Board Computer 1976 Manuals Included on ebay .. to dear for an untested system like it.
5 or you could go the route of a SBC back plane slightly later for like us$47 and mount it in a timber or metal box, and add psu, SBC card and go from there
typical backplane
typical SBC -- GES 9022-386SX PCA PCB SBC Single Board Computer
http://www.ebay.com/itm/PICMG-SBC-B...760941?hash=item463c4366ed:g:fbMAAMXQ01tRTd-j