They are actually really easy to replace, the pump needs to come out to do it though so I would run out of other things before you decide to do the seals. They are also pretty cheap to buy, you can find comeplete pump seal kits, including the front main seal, for like $30.
Finding a good working pump shouldnt be too hard or expensive, they arent that valuable, the IDI non-turbo pumps. Youd be looking at $200 at the most, maybe $400 for one thats been gone through.
Check out vwdiesel.net they have a bunch of walk-throughs and trouble shooting advice.
This company has had some good reviews on Vwdiesel.net, fully rebuild pump $435 shipped, you need to send them your old pump, though.
http://www.thedieselstore.com/templa...11172691117270