Did the guy check for Diagnostic Trouble Codes (DTC)? If any, what are they? That story about "it's hacking so much air thru the leaky gasket" sounds like BS to me. If this is indeed happening (which I doubt), a simple compression and/or cylinder leakdown test will easily detect it. Has this been done? I doubt it. I don't think I've every heard of, or read (on all the Jeep forums) of anyone having a head gasket problem, except when someone had previously tampered with the engine. Is there coolant in the oil, or oil in the cooling system? There is a multitude of things that will keep the engine from starting, and a head gasket problem is probably the biggest "stretch" of all. The engine has either 4-5 more cylinders that should fire....or at least try to, assuming it is blown and how it is blown....into one cylinder or between two cylinders. Did the guy check for fuel....fuel pump operation and/or pressure test? How about the fuses/relays for the fuel system? Did he check for ignition (spark at the plug(s)? These are the easy (and first) things that should be checked. Good luck on this one. If that's all the better this guy can do, I'd think about taking it somewhere else for a good check.
The same goes for the blower switch. Any DTC's? If so, what are they? The HVAC systems on these is very different from a few years ago, and are quite complex. This could also be any number of things, with the switch being only one of them. Has it been checked in both "Auto" and "Manual" modes? Is it the same in both? Has the appropriate fuse(s) in the Forward Control Module (FCM) been checked? I doubt it.
Edit: I just looked at the link. If you're not savvy on these things, you definitely need to have it looked at by a knowledgeable (with Chrysler products) mechanic. Everything should be checked closely. The mileage is not that high so as to have a major engine problem. First look for evidence of tampering and/or "Mickey Mouse" fixes/repairs on any system in the vehicle. Should be easy to tell. Again, good luck.
06 GCO, Dk Khaki, QDII, Flshing Hi 3rd Bk Lt, MDS "ON" Lt, Airtab Vortex Gens, Debadged, Fumoto Drain Valve, BT Catch Can, Chopped EGR Tube, SRT8 CAI, K&N Filter, Sonnax Trans Line Press Booster, SC Tuner W/Adv Trans Tune App, DS Tuner, Cust tubular hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvr, SRT8 frt/rear bumpers, FRI Sidewinder Cam/6.1 valvetrain, SLP 25% UD Pulley, BBK true 90mm T-Body, SOS Ign Coils w/.060 spark plug gaps, SRT Reps with 265/45&295/40X20's.
Run a carfax regardless, mainly to see how many previous owners, because if there's 6 you might have issues. I agree with 90 above, sounds like the guys trying to use common terms like (head gasket) to make you think it'll be a simple mechanic fix (Not the case).
If you're hell bent on this thing, i'd get it towed to a mechanic and get a second opinion. Because spending $200 on tow and diagnostics is better than a $6,000 lawn ornament.