I use the Stoney Point tools myself and have found them to be quite satisfactory and cost effective. To do the headspace measuring, you will need a decent dial caliper, the B-2000 body and the appropriate bushing. (The 7mm-08 uses bushing #D -0.400", but I don't know that they have one for the Hornet.) The B-2000 body is what attaches to the caliper and is what the headspace bushings and comparitor inserts for measuring OAL to the ogive fit into.
The OAL gauge is a separate tool and is used in conjunction with the caliper, B-2000 body, and appropriate insert. The OAL gauge also requires an appropriate cartridge case that is drilled and threaded through its base to fit the OAL tool. These cases aren't very expensive, but you could do your own with the appropriate drill and tap. The drill size and tap thread are not of a common size and pitch. I don't now remember what that size and pitch is, but maybe someone else on this forum will know.
The Stoney Point Overall Length gauge averages about $26. The associated cartridges average about $6 each. The Comparator body runs about $14, headspace gauge bushings average about $7 each, OAL inserts about $3.50 each. One can buy the headspace gauge set with body and 5 bushings for about $34. Another way is to buy the comparator with 6 OAL inserts for about $25 and then buy the headspace 5 bushing set for another $25.
Quite frankly I don't care for the Lee Case Trimmer. It's okay, I suppose, for small quantities if you are satisfied with one fixed case length and don't mind the time it takes to use it. Sooner or later, though, I think that you will opt for a bench mounted case trimmer of some sort.
