I'm looking to buy an engine compression tester for 616/7 diesel
engines.

At the cheap end, there is Harbor Freight.
$25
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93644

Ooooh, look a $150 deluxe set from Harbor Freight!
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46800

At the higher end there is Snap ON  - $180 for the tester and $60 for
the adapter
http://buy1.snapon.com/products/diagnostics/mt33c.asp?partno=MT33C&dir=catalog
http://buy1.snapon.com/catalog/item.asp?search=true&item_ID=11128&PartNo=M3542A&
group_id=1430&supersede=&store=snapon-store&tool=all

So is the Harbor Freight stuff decent/acceptable?  Are there any
mid-range brands to look at?

Thanks

Jay