well car-part.com for junkyard parts, rockauto.com for misc new parts, ebay for rest. There are numerous Tachs and dashes for sale on ebay but they wont have any instructions, if u gonna modify something like that, u should have a full wiring diagram for whatever car u take em of and another for one u will put it onto. Else i wouldnt recommend modifying anytihng, its get tricky. u can also get some body kits if u want to waste money on those, check out the STICKEYS in the main Tercel section. One of them has a PDF, inside are a lot of links and reviews to them, its a bit outdate but kicks butt
To save money, I would recommend u remove your equipment, and simply paint it. U can get good oil based permanent paint of some sort and paint it on with a small brush, u can save a lot of money, and get the exact look u want. Make sure the paint u get can stand heat and sun, u can aslo use some sort of plastic polish to polish ur dash glass, and such making ur car look brand new.
hope that helps