I'd take the discounted mount from CO ski & golf. I'd also check the measurement for the recommended mark on all 4 skis to make sure they're consistent. Often those mounting points are part of the skis top sheet graphics, and are not consistent from ski to ski. I'd probably measure the distance from the recommended line to either the tip or tail, take the average from all 4 skis, and clearly mark on all 4 (in sharpie) where you want them mounted, which may not be exactly where the MFR placed their graphic or scribe line. Point out your "correct" mounting line to the tech you hand the skis off to, and confirm that they were mounted as instructed when you pick them up.
If they're mounted improperly after that, you should have some recourse for compensation, but that compensation may vary widely depending on the shop's policy, how far off they are, and how motivated the tech/mgr are to keep a satisfied customer.
I haven't ever needed to ask for a new ski tune. Most reputable brands come from the factory with a decent tune, but you might want to check that the bases have some structure from a stone grind, aren't base or edge high, by checking with a straight edge, and have at least one coat of all-purpose wax applied. It probably wouldn't hurt to ask for an additional waxing, preferably for whatever temps you anticipate encountering on your first day out, or an all-purpose that should at least help to impregnate the base structure.
I'm kind of a big fan of detuning tips and tails, but find I only really need to do this after a shop tune. Pretty much all of the factory tunes I've had on new skis in the last decade have been fine out of the wrapper, with the exception of one boutique brand which to be honest, I expected better from. Meh, those skis were overrated anyway, and I ended up eating the cost of a shop tune, but still covering the cost of their replacements when I sold them after a dozen or so days of use.
I know a lot of people who recommend mounting your own bindings, but personally never saw the point. Shop jigs IMO>paper jigs, and any reputable shop should torque test your bindings once mounted. Most people can't accurately torque test at home, and release values may vary from one binding to another, with the same din setting. Yeah, most of the time those release values are "close enough", but if they're not, a DIY'er probably won't be able to detect, or adjust for it, and if a shop tests a binding, and it fails, they might be able to arrange for a warranty replacement. This is probably an unlikely scenario, but is probably worth the $30 price of admission.
Finally, if you do decided to got the DIY route, use the right tools for the job, and always measure twice, and (hopefully) drill only once, or say hello to my little friend, the helicoil.
IME, most techs appreciate a frosty brewed beverage tip, but it might be advisable to withhold said tip until the bindings are successfully mounted.