http://www.dillondynamometers.com/digital.htm

I have the EdJunior, 5000 lb capacity. Their list is about $1300, but you can get them discounted, I think I paid around $800 for mine new (but also a couple of years ago).

Yes, it would be very easy to put in line: just tie one shackle to your snubber line, the other to another line to the bits. Its IP55, so sort of water resistant. When I was measuring running rigging loads, I tied it to the line under test with a rolling hitch, tied the other end off to a cleat, then eased the line under test letting the dynamometer take the load. That's probably the best way to do it, you can then re-tension the line under test and remove the Dillon without a fire drill. One problem is that it is sharp cornered and weighs about 10 lbs or so, the potential is there so scratch up your brightwork if you don't take precautions.

You might take a look at used mechanical ones. Many of them (depends on the model) have tell tales - little tabs or needles that get bumped by the main needle - that will save the high and low readings. The accuracy is perfectly adequate for this sort of thing.

I had a CQR but found it would not bite in certain conditions. On one occasion I tried several attempts with the CQR then threw the Bruce over - bit instantly. I used the Bruce after that. The Bruce has not done stellar in tests yet always seems to set. However they are no longer made, and I don't have any confidence in the copies. Just looking at them you can see they aren't an accurate copy. I currently have a Spade with a genuine Bruce kedge. The Spade seems to work well and is self launching, a definite plus for me.