What you're going to have to do is beat them up and make the helmet a condition of the sale: IOW, "I won't sign unless you include the helmet..."
Now, Please accept this in the spirit of a gentle prod, as I don't mean to flame, be 'Holier Than Thou', or come off as being gratuitously smart~a$$ed:
But it never fails to amaze me that so many people will spend $8, $9, $10, $11,000 on a motorcycle (plus $1000 for a pipe/PCIII, etc etc etc...) and then use a freebie brain bucket, $150 KBC lid, and/or complain about the price of decent gear.... Especially if you're financing. Geez... Throw it all in a pile, and have the dealer call the finance company with the total. I mean, does it *really* matter if your payments go from $200/month to $210???
Anyways - Ask the dealer to include gear as part of the package, and see where that gets you.
Not about to put that theory to the test, but the cheaper helmet won't be as comfortable, and won't be as durable (lifespan wise).
Does it have a removable and washable liner? Helmet~Funk sucks...
Does it have replacable cheek pads? to customize and restore fit...
Does the vent system actually work?? Or does it just make noise?
(Most Important) Does it fit tightly enough that you can't twist it off to the side by grabbing the chinbar and pulling, yet is comfortable enough to wear for 300+ miles without giving yourself a headache??
Razor sharp graphics??
Easily replacable shield??
If you can find all those qualities in a $150 helmet, then God Bless...
Not to get of topic here but why do people need $500 helmets?
The KBC VR1 Euro has Snell/DOT certs, fully removable liner, removable cheek pads, adequate ventilation, and great graphics. You can get it helmetcity for $130.