If you know nothing about bows, maybe you shouldn't buy one.
That was easy.
Get on eBay and see what comparable bows, or examples exactly like that one, are going for. That should give you a decent ballpark guess at what they're worth.
Bear is a respected manufacturer in the bowhunting industry. They make good stuff. And good stuff from a respected manufacturer is going to cost more than similar from some unknown maker, so bear that in mind.
"Bear" in mind. Get it? I'm hilarious.
SHTF scenarios are more and more in the forefront of my mind, these days. I read "One Second After," by William Forstchen (spelling?) and it set my teeth on edge. Bugout bag? Yeah, got that. Emergency kit in the car? Got that, too. I even have a vehicle, of sorts, that will function in spite of an EMP attack: an old Farmall tractor with magneto ignition. If you can turn the crank, it'll start and run. And backup ignition hardware in a steel tin set aside for the Toyota (carbureted, so all I have to do is have backups for the ignition hardware, no computer bits to worry about). So my previous, glib answer was uncalled-for and I apologize for that; you have a completely legitimate interest and I was a jerk.
Quick check on eBay shows Whitetails and Whitetail IIs moving at a high average of about $130, lows down around $65; a couple of outlier prices over $200 that seemed to include a lot of accessory equipment, nice but not crucial.
Me, I do some practice with a couple of cheap longbows. One's kind of nice, one's merely fair and has what could charitably be described as a fine rope instead of a bowstring. But it'll hit what you aim it at out to about 40yds and that's enough to get some dinner in a pinch. The beauty there is that what it really is, is a stick. A stick with a string. If you have some time and a few basic hand tools, you can split out a stave, steam and bend it to suit your needs, and make your own. I tried it once and got results that could charitably be described as lousy, but it held the string and it made an arrow go somewhere, so with practice I could do better. The really crucial bit was: no moving parts, reproducible with no electricity and only the most basic of tools.
Anyway: don't let the dude rip you off. If it's just the bow and he wants more than $130, he's being rude.