Trees range in price according to species and height. At the lot they'll have them divided by both. (ex: 6' douglas = $15, 6' noble = $60)
SUPER easy to care for. Just add water. Getting them set up fir that is slightly harder.
Most important thing is that it goes in water within 10 minutes of cutting off the bottom inches. After that the sap forms a seal on the trunk that keeps it from drawing water. So it dies very very quickly once in a warm house (they can live for weeks and weeks cut OUTSIDE, because it's cold, and usually wet).
Second most important thing is that there's SPACE between the bottom of the trunk and the bottom of the stand. If it's sitting flush against the bottom, it also won't draw water. Easy fix... have them cut it (or cut it yourself) at an angle. Then when you stab it on the spike it's never flush against the bottom. The screws that you tighten on the stand hold it upright, not the bottom of the stand.
3rd (is still a water thing), make sure there's a couple inches of water above the cut. Sounds simple, but it can be awkward. I make this a kid-job to reach in and find out. I also make it a kid job to water it! My 'responsibility'...but their bendy little bodies doing the work :)
4th; if you have pets JUST USE PLAIN WATER. They have scented packets and extended life packets. A plain water tree will last for 1-2 months indoors as long as it never goes dry (allowing the cut to seal with resin). PETS LOVE XMAS TREE FLAVORED WATER. They just do. Every cat and dog I've ever met sneaks in under there for that water. They're usually careful about it, but they drink it. The additives are poisonous. And an unnecessary expense.
But that's ALL you have to do to care for it: make sure it CAN drink water, and that it has water.
Needle mess... they only drop needles as they're drying or being whacked about. So whack it about FIRST (outside your house) to shake any loose ones off, and vacuum after you've bashed it about getting it "straight" in the stand (have one person look, one person hold the trunk and turn, and one person do the screws. Or if there's only two of you, the screw turner looks. If there's only one of you, it will take a WHILE. Kids can hold the trunk as well.) DO look from a few different angles. As it will look "straight" when it's tipping BACK. Once you turn the tree... oh. Okay. Pull it that way. THEN, once you're done schlepping, spiking, and positioning the tree... vacuum. You won't have a needle problem as long as it's nice and watered. Maybe 5 or 6 a day.