The only mk5 wagons for TDI was the 2009 Jetta sportwagen. 2010+ they're technically mk6.
The mk4 was sold until 2005. So the prices for the 2002-2005 are low enough so that I wouldn't buy a junk car. The 2009 are high enough so that there aren't many junky ones out there.
As long as the body is good, the suspension can be replaced and the engine can be brought up to maintenance specs, so it really depends on your budget and if you're DIY or paying someone else to fix it up.
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