OP - Dude.... no offense but if you think you will find a CRD with under 50k (07 and 08) until the new 2014 actually comes out someday..... you probably should be looking at another vehicle. My 07 has 102k on it and I bought it in early 09 for $ 28k (pinched dealer in really down market) as one of the fuel recovery Jeeps and only had 7k on it then and now at 100+K, Maybe you will find one but don't worry about the mileage - worry about maintenance. Just paid mine off and checked KBB and other sites and still worth $14-19k and ours is a Limited with every available option other than fold in mirrors has rear DVD, etc TOW IV, etc. Some online sites don't usually even recognize a diesel was made in this model so be careful.
If you can find one with good records - BUY it. The MB 6 cyl diesle engine is a pure and solid engine and really matched well with this tranny and weight vehicle. Good luck. Are there issues - yes but nothing systemic with engine and ALL are known and this forum will help. Welcome.
2007 WK Limited 3.0 CRD - Stock (Mine)
2010 XK Sport 5.7 Hemi - Stock (Wife)