I'd say for your "mexican rebuild", you're looking at around $100-$200 US in parts. Plus extra for tools, depending on what you need. There are a bunch of places on-line you can price out parts at yourself. For example,
www.worldimpex.com. There are many other parts sources that can quote you on-line (do some searching around.) Or you might check with altrom, as they supply many engine internal parts (although be warned they generally don't sell directly to retail):
http://www.altrom.com/Also check for yourself, but mechanics generally charge labor and mark up on parts as well. I'd guess maybe 8 hrs work, so at $60/hr, that's a few hundred dollars in labor. The total cost could push $1000 US. A mechanic also likely wouldn't warranty the work since it's not being done "by the book" (which would be to pull the whole engine, ship it off to an engine rebuilder to have it "properly" rebuilt and reinstalled, all to the tune of more around $2000+ US.) But then you'd have a rebuilt head, new fresh pistons and block and crank, the longblock should be entirely in "new" specs, and you should have peace of mind it will be good for hundreds of thousands of miles.
You could also pull the engine, remove all the accessories, have the longblock rebuilt by a specialist engine rebuilder, and then reinstall it yourself along with all the accessories. When I had my 1.6lTD longblock rebuilt a few years ago, I recall the price for the rebuild being about $1000-$1200 US area.
Edit: using the
search feature of our board (don't forget to try the search feature before asking questions here), I found a thread on canadian parts suppliers:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=1382