Dive on it. 185k is nothing for those vans.
Injectors can be a bit expensive, esp if they are carboned up because they can be a nightmare to remove, however - find a good local diesel mechanic, it shouldn't get too expensive to fix. Tell whoever is doing it IF it ever needs to happen - oven cleaner.
Used injectors can be had for pennies on the dollar, I have used used ones several times before, if you get them from the guys below you'll have no worries.
As far as the tranny's, you can find used ones all day for $1000-1400, rebuilt ones from $1800-2500.
www.qualitysprinter.com for used parts, egr's, turbo boots, injectors, etc etc - GREAT prices, and REALLY good guys there - they also sell rebuilt parts.
http://store.europarts-sd.com - good for filters, brakes, belts, lights, and most new parts - you can get new oem parts for 20-50% under dealer list here - another good co. fast shipping.