to get your brand spanking new 1.9, check for a dealer near you
http://www.overlandparts.com/dealerlist.htmYou can get both TDI's and IDI' s, but... I have a friend who does lots of these, and he has not had good experience with TDI's and mechanical pumps, just not enough Pressure to get performance. (he can still get new 1.9 Long Blocks for ~$2000) you can add 1.6 TD stuff. While this is alot of $$$, if you are going to keep the thing for life (you can always drop it into any VW-d (or gasser)) 1976-1999 with little mod (16mm exhaust spacer) if you have to rebuild a 1.9, you might have $500 in parts + head work $500
Other option, if you are real handy, is to buy a wrecked TDI and swap it in (early is better, pre 1999.5) these go for ~$2500 - $3500 for complete wreck. You want the whole car, as you will need lots of parts and wiring harness. A TDI is nice for quieter, more power and better performance.
I like the 1.9 in Caddy and vans for extra torque, but in a car they are not much different than a healthy 1.6TD (which are much easier to find, and easier to get parts)